Cancers of the urinary tract among American Indians and Alaska Natives in the United States,...

An Update on Cancer in American Indians and AlaskaNatives, 1999-2004

Supplement to Cancer

Cancers of the Urinary Tract Among American Indiansand Alaska Natives in the United States, 1999–2004

Robin Taylor Wilson, PhD1

Lisa C. Richardson, MD, MPH2

Janet J. Kelly, MS, MPH3

Judith Kaur, MD4

Melissa A. Jim, MPH2,5

Anne P. Lanier, MD, MPH3

1 Division of Epidemiology, Department of PublicHealth Sciences, Pennsylvania State College ofMedicine, Hershey, Pennsylvania.

2 Division of Cancer Prevention and Control, Cen-ters for Disease Control and Prevention, Atlanta,Georgia.

3 Alaska Native Tribal Health Consortium, Anchorage,Alaska.

4 Department of Oncology, Mayo Clinic, Rochester,Minnesota.

5 Division of Epidemiology and Disease Prevention,Indian Health Service, Alburquerque, New Mexico.

BACKGROUND. Assessment of the kidney parenchyma (‘‘kidney’’) and urinary

bladder (‘‘bladder’’) cancer burden among American Indians and Alaska Natives

(AI/AN) has been limited. Using a database with improved classification for AI/

AN, the authors described patterns of these 2 cancers among AI/AN and non-

Hispanic whites (NHW) in the United States.

METHODS. Cases diagnosed during 1999 to 2004 were identified through National

Program of Cancer Registries and the Surveillance, Epidemiology and End Results

program and linked to the Indian Health Service (IHS) registration records. Age-

adjusted incidence rates, rate ratios (RR), annual percent change, and stage at

diagnosis were stratified by IHS Contract Health Service Delivery Area (CHSDA)

counties to adjust for misclassification.

RESULTS. Kidney cancer incidence among AI/AN in CHSDA counties exceeded

that among NHW (RR, 1.51; 95% confidence interval [CI], 1.42-1.61), and was

highest among AI/AN in the Northern Plains, Southern Plains, Alaska, and South-

west. Average annual increases were highest among AI/AN (5.9%) and NHW

(5.9%) males aged 20 to 49 years, although statistically significant only among

NHW. Conversely, bladder cancer incidence was significantly lower among AI/AN

than NHW (RR, 0.40; 95% CI, 0.37-0.44). For both sites, AI/AN were significantly

less likely to be diagnosed at an earlier stage than NHW.

CONCLUSIONS. AI/AN have about 50% greater risk of kidney cancer and half the

risk of bladder cancer than NHW. Although reasons for these enigmatic patterns

are not known, sustained primary prevention efforts through tobacco cessation

and obesity prevention are warranted. Cancer 2008;113(5 suppl):1213–24. Pub-

lished 2008 by the American Cancer Society.*

KEYWORDS: cancer, incidence, American Indian, Alaska Native, misclassification,NPCR, SEER, United States, health disparity.

C ancers of the kidney and urinary bladder (‘‘bladder’’) are not

currently a focus of cancer control and prevention efforts, in

part because of the lack of evidence-based screening methods.

Previous reports indicate racial/ethnic differences in the incidence

of these cancers, including higher incidence and mortality rates

of kidney cancer among American Indians and Alaska Natives

(AI/AN).1-3

Analyses of cancer patterns among AI/AN have been limited by

considerable race misclassification of AI/AN cases in many central

cancer registries.4-7 The aim of this study is to provide a compre-

This supplement was sponsored by CooperativeAgreement Number U50 DP424071-04 from theCenters for Disease Control and Prevention, Divi-sion of Cancer Prevention and Control.

The findings and conclusions in this report arethose of the authors and do not necessarilyrepresent the official position of the Centers forDisease Control and Prevention.

Address for reprints: Robin Taylor Wilson, PhD,Division of Epidemiology, Department of PublicHealth Sciences, Pennsylvania State College ofMedicine, 600 Centerview Drive, Mail CodeA210, Hershey, PA 17033; Fax: (717) 531-5779;E-mail: [email protected]

*This article is a US Government work and, assuch, is in the public domain in the United Statesof America.

Received May 5, 2008; accepted June 3, 2008.

Published 2008 by the American Cancer Society*DOI 10.1002/cncr.23733Published online 20 August 2008 in Wiley InterScience (www.interscience.wiley.com).

1213

hensive description of kidney and bladder cancer in

AI/AN populations using techniques to lessen the

effects of race misclassification. The database used

in this analysis provides the most accurate and com-

plete racial/ethnic classification of AI/AN diagnosed

with cancer in the United States to date.

MATERIALS AND METHODSCancer Case AscertainmentNewly diagnosed cancers of the bladder and kidney

parenchyma (‘‘kidney’’) diagnosed during 1999 to

2004 were identified in US population-based cancer

registries participating in the National Program of

Cancer Registries (NPCR) of the Centers for Disease

Control and Prevention (CDC) and the Surveillance,

Epidemiology, and End Results (SEER) program of

the National Cancer Institute (NCI). More detailed

methodology can be reviewed elsewhere in this Sup-

plement.8

Analysis of cancers of the kidney included all

invasive cancers. Primary site and histology were

coded according to the International Classification of

Diseases for Oncology (ICD-O) edition in use at the

time of diagnosis and converted to the Third Edition

(ICD-O-3).9 Kidney cancer analyses focused on can-

cers of the kidney parenchyma (ICD-O-3 site code

C64.9) and renal cell carcinoma overall, according to

the Mainz classification(ICD-O-3 morphology codes

8310, 8312, 8317, 8318, and 8260).10 Surveillance

reports on kidney and other cancers frequently group

the kidney parenchyma and renal pelvis into a com-

posite rate; to facilitate comparisons with other

reports, data for kidney and renal pelvis combined

(ICD-O-3 site code C65.9) are provided online at

http://www.cdc.gov/npcr.

Analysis of cancers of the urinary bladder (ICD-

O-3 site code C67.9) included patients with both

invasive and in situ cancers.11 We examined data for

all histologic types combined, as well as for transi-

tional cell cancers only (ICD-O-3 morphology codes

8120, 8130, and 8050).

Classification of Race and EthnicityThe database was created by linking cancer registry

data to the Indian Health Service (IHS) patient regis-

tration database. The IHS registration database con-

sists of persons from federally recognized tribes in

the US eligible for IHS services. Individuals whose

race or ethnicity was previously classified in partici-

pating cancer registries as white, other, or unknown,

and then identified as AI/AN by linkage with the IHS

data, were reclassified as AI/AN. Probabilistic data

record linkages were conducted using CDC’s software

LinkPlus. Cases were also classified by Hispanic ori-

gin using the North American Association of Central

Cancer Registries Hispanic Identification Algorithm.12

All AI/AN were included in AI/AN rates irrespective

of Hispanic origin.

Geographic RegionsGeographic regions used for this study were consist-

ent with those used in previous reports.3,13 Contract

Health Service Delivery Area (CHSDA) counties are

designated by the IHS and consist of 624 counties

that, in general, include or are adjacent to federally

recognized tribal lands,8 and include approximately

56% of the AI/AN population. CHSDA counties have

been used previously2,3 for rate calculations, as there

is evidence that less race misclassification occurs in

these counties.14 In this study, we calculated inci-

dence for CHSDA counties and for all counties com-

bined. IHS regions and CHSDA counties included in

the analysis are shown in Figure 1.

Statistical Analysis

Incidence, annual percent change, and rate ratios. In-

cidence rates were calculated for cancers of the kid-

ney and bladder for 6 geographic regions by sex and

by age group, using NCI’s SEER*Stat software (ver-

sion 6.3.6).15 SEER*Stat uses bridged single-race

population estimates as denominator data, devel-

oped jointly by the US Census Bureau and CDC, and

further modified by NCI.8,16 AI/AN incidence rates

were adjusted for age using the direct method with

the 2000 US standard population.17 Age-adjusted

incidence rates were calculated for 2 age groups: 20

years to 49 years, and 50 years and older. Rate ratios

(RR) were calculated to compare incidence rates

between AI/AN and NHW. Ninety-five percent confi-

dence intervals (CI) were calculated in SEER*Stat

using methods described elsewhere.8 The annual

percent change in incidence rates was calculated

using weighted linear regression techniques and

2-year moving averages.15 Correlations between re-

gional incidence rates in CHSDA counties and self-

reported tobacco use prevalence among AI/AN in

CHSDA counties18 were calculated using the Pearson

correlation coefficient.

Stage at diagnosisSEER Summary Stage 2000, age-adjusted to the 2000

US standard population, was used to describe the

distribution of stage at diagnosis.8 The statistical sig-

nificance of differences between AI/AN and NHW

stage distribution were determined using the chi-

1214 CANCER Supplement September 1, 2008 / Volume 113 / Number 5

square test. Because of inconsistencies between

SEER Summary Stage 2000 and SEER Summary Stage

1977, we report stage data from 2001 to 2003 only.19

RESULTSCancer IncidenceAmong AI/AN only, incidence rates in CHSDA coun-

ties were higher than in all counties combined

(CHSDA 1 non-CHSDA). Consistent with other stu-

dies, this difference suggests that misclassification of

AI/AN race is greater in the non-CHSDA counties

(Tables 1 and 2). Therefore, our presentation of

results will focus on CHSDA counties.

For cancer of the kidney parenchyma, incidence

rates in CHSDA counties for both sexes combined

ranged from 11.7 (Pacific Coast) to 23.7 (Northern

Plains) among AI/AN and from 11.1 (Southwest) to

12.7 (East) among NHW (Table 1). Overall, incidence

rates were nearly 1.53 higher among AI/AN com-

pared with NHW, and rate ratios comparing AI/AN

with NHW were significantly elevated in all regions

except the Pacific Coast and East. Rate ratios were

somewhat higher among AI/AN females (RR, 1.71;

95% CI, 1.55-1.88) than AI/AN males (RR, 1.40; 95%

CI, 1.29-1.52), with highest rate ratios (�2.5-fold

higher) among AI/AN females in the Northern and

Southern Plains. For all regions combined, these

results were similar for renal cell histologic subtypes.

In CHSDA counties, urinary bladder (‘‘bladder’’)

cancer incidence rates for transitional cell cancers

and all bladder cancers combined were significantly

lower among AI/AN (9.6) than among NHW (23.9)

(Table 2). This pattern was similar in all regions.

Incidence rates varied approximately 4-fold among

AI/AN, from 3.2 in the Southwest to 14.8 in the

Northern Plains. Rate ratios ranged from 0.13 (95%

CI, 0.10-0.18) in the Southwest to 0.74 (95% CI, 0.64-

0.86) in the Southern Plains.

Age-Specific Incidence RatesKidney cancer incidence among AI/AN aged 20 years

to 49 years were highest in the Northern (8.6) and

Southern Plains (8.4), ranging roughly 2-fold region-

ally (Table 3). Regional patterns in incidence rates

among AI/AN aged 50 years and older were similar

to the younger age group, although rates in Alaska

were also significantly higher. Over the time period

of the study (1999-2004), incidence rates among AI/

AN and NHW males in both age groups increased.

Average annual percent increases were slightly higher

among males aged 20 years to 49 years, compared

with males aged 50 years and older, among both AI/

AN (5.9% per year vs 3.2% per year) and NHW (5.9%

vs 3.0%) males, respectively, although the increases

were statistically significant only among NHW. There

was not a significant trend over time among AI/AN

FIGURE 1. States and Contract Health Service Delivery Area (CHSDA) counties by Indian Health Service Region are illustrated.

Urinary Tract Cancer in AI/AN/Wilson et al 1215

TABLE

1Kidne

yPa

renc

hymaCan

cerIn

cide

nceby

Indian

Hea

lthSe

rviceReg

ionforAmerican

Indian

s/Alask

aNatives

aan

dNon

-Hispa

nicWhites,

UnitedStates,1

999to

2004

CHSD

ACou

nties

AllC

ount

ies

IHSReg

ion

Sex

AI/A

N

Cou

ntb

AI/A

N

Ratec

95%

CIfor

AI/A

NRate

NHW

Rate

RateRatio

c

(AI/AN

:NHW

)

95%

CIfor

RateRatio

AI/A

N

Cou

ntb

AI/A

N

Ratec

95%

CIfor

AI/A

NRate

NHW

Ratec

RateRatio

c

(AI/AN

:NHW

)

95%

CIfor

RateRatio

NorthernPlains

Both

sexes

203

23.7

20.4-27.5

12.1

1.96

d1.68

-2.28

251

17.0

14.8-19.4

13.0

1.31

d1.14

-1.50

Male

117

28.6

23.3-34.8

16.1

1.77

d1.44

-2.16

145

21.1

17.4-25.3

17.4

1.21

0000

000

1.00

-1.45

Female

8619

.215

.1-23.9

8.6

2.22

d 000

001.75

-2.78

106

13.4

10.8-16.4

9.3

1.44

d1.16

-1.76

Alaska

eBo

thsexes

7819

.615

.3-24.7

12.7

1.54

d1.16

-2.03

7819

.615

.3-24.7

12.7

1.54

d1.16

-2.03

Male

5228

.620

.7-38.3

18.0

1.59

d1.10

-2.25

5228

.620

.7-38.3

18.0

1.59

d1.10

-2.25

Female

2612

.07.7-17

.67.9

1.51

0.92

-2.40

2612

.07.7-17

.67.9

1.51

0.92

-2.40

Southe

rnPlains

Both

sexes

297

21.3

18.9-23.9

12.4

1.72

d1.52

-1.94

324

16.7

14.9-18.7

13.8

1.21

d1.08

-1.36

Male

163

24.7

20.9-28.9

17.1

1.45

d1.22

-1.71

177

19.0

16.2-22.2

18.8

1.01

0.86

-1.18

Female

134

17.9

15.0-21.2

8.6

2.09

d1.73

-2.51

147

14.4

12.1-16.90

09.6

1.50

d1.26

-1.77

Pacific

Coa

stBo

thsexes

169

11.7

9.9-13

.811

.31.04

0.87

-1.22

201

7.7

6.6-8.9

11.1

0.69

d0.59

-0.80

Male

9714

.611

.5-18.2

15.6

0.94

0.74

-1.17

119

9.8

8.0-12

.015

.40.64

d0.52

-0.78

Female

729.4

7.2-11

.97.7

1.22

0.94

-1.56

825.9

4.6-7.4

7.5

0.79

d0.62

-0.99

East

Both

sexes

4612

.99.3-17

.312

.61.02

0.74

-1.37

163

6.3

5.3-7.4

12.9

0.49

d0.41

-0.57

Male

2012

.37.1-19

.617

.60.70

0.41

-1.12

876.8

5.3-8.5

17.7

0.38

d0.30

-0.48

Female

2613

.38.6-19

.68.5

1.56

d1.01

-2.30

765.7

4.4-7.1

9.0

0.63

d0.49

-0.79

Southw

est

Both

sexes

341

17.9

15.9-19.9

11.1

1.60

d1.43

-1.80

352

16.3

14.6-18.2

10.9

1.50

d1.34

-1.67

Male

206

25.0

21.5-28.9

15.0

1.67

d1.43

-1.93

216

23.2

20.0-26.7

14.8

1.57

d1.35

-1.81

Female

135

12.4

10.3-14.7

7.8

1.59

d1.32

-1.91

136

11.1

9.2-13

.27.6

1.45

d1.21

-1.73

Total

Both

sexes

1,13

417

.916

.8-19.0

11.8

1.51

d1.42

-1.61

1,36

912

.311

.6-13.0

12.6

0.98

0.92

-1.03

Male

655

22.7

20.8-24.6

16.2

1.40

d1.29

-1.52

796

15.6

14.4-16.8

17.2

0.91

d0.84

-0.98

Female

479

13.9

12.7-15.2

8.1

1.71

d1.55

-1.88

573

9.6

8.8-10

.48.8

1.09

1.00

-1.19

Totalren

alce

llBo

thsexes

992

15.6

14.6-16.6

10.0

1.56

d1.46

-1.67

1,19

910

.710

.1-11.4

10.6

1.01

0.95

-1.07

Male

574

19.7

18.0-21.5

13.7

1.44

d1.31

-1.57

695

13.5

12.4-14.6

14.6

0.92

0.85

-1.00

Female

418

12.1

11.0-13.4

6.8

1.79

d1.62

-1.98

504

8.4

7.7-9.2

7.3

1.15

d1.04

-1.25

Source

:Can

cerregistrie

sin

theNationa

lProgram

ofCa

ncer

Registrie

s(N

PCR)

oftheCe

ntersforDisea

seCo

ntrola

ndPrev

entio

nan

d/or

theSu

rveilla

nce,

Epidem

iology,a

ndEn

dRe

sults

(SEE

R)prog

ram

oftheNationa

lCan

cerInstitu

te.

CHSD

Aindica

tesCo

ntract

Hea

lthSe

rviceDeliveryAr

eas;

IHS,

Indian

Hea

lthSe

rvice;

AI/A

N,A

merican

Indian

s/Alaska

Natives;N

HW,n

on-H

ispa

nicwhites;

CI,c

onfid

ence

interval.

aAI/A

Nrace

isrepo

rted

byNPC

Ran

dSE

ERregistrie

sor

throug

hlin

kage

with

theIH

Spa

tient

registratio

nda

taba

se.A

I/AN

person

sof

Hispa

nicorigin

areinclud

ed.

bRa

tesarepe

r10

0,00

0pe

rson

san

dareag

e-ad

justed

tothe20

00USstan

dard

popu

latio

n(19ag

egrou

ps,C

ensu

sP2

5-11

30).

cRa

teratio

sareca

lculated

inSE

ER*Statp

riorto

roun

ding

ofratesan

dmay

note

qual

rate

ratio

sca

lculated

from

ratespresen

tedin

thetable.

dRa

teratio

isstatistic

ally

sign

ifica

nt(P

<.05).

eRa

tesan

drate

ratio

sforAlaska

intheCH

SDAco

untie

ssectionarethesameas

thos

ein

theAllC

ountiessectionbe

caus

eallc

ountiesin

Alaska

areCH

SDAco

untie

s.

Yearsof

data

andregistrie

sus

ed:1

999to

2004

(41states

andtheDistrictof

Columbia):A

laska,*Alab

ama,*Ar

kans

as,A

rizon

a,*Ca

lifornia,*Co

lorado

,*Co

nnec

ticut,*

theDistrictof

Columbia,

Delaw

are,

Florida,*Geo

rgia,H

awaii,Iowa,*Idah

o,*Illinois,

Indian

a,*Ke

ntuc

ky,L

ouisi-

ana,*Massach

usetts,*

Maine

,*Michiga

n,*Minne

sota,*

Misso

uri,Mon

tana

,*North

Carolin

a,*Neb

raska,*New

Ham

pshire,N

ewJersey,N

ewMexico,*Nev

ada,*New

York,*

Ohio,

Oklah

oma,*Orego

n,*Pe

nnsylvan

ia,*

Rhod

eIsland

,*Te

xas,*Utah,*Washing

ton,*Wisco

nsin,*

West

Virginia,a

ndWyo

ming*;1

999an

d20

02to

2004

:North

Dak

ota*;2

001to

2004

:Sou

thDak

ota*;2

003to

2004

:Mississippi*an

dVirginia;2

004:

Tenn

essee.

*Stateswith

atleasto

neco

unty

design

ated

asCH

SDA.

Percen

tage

region

alco

verage

ofAI/A

Nin

CHSD

Aco

untie

sco

mpa

redwith

AI/A

Nin

allc

ounties:

Alaska

510

0%;E

ast5

13.1%;N

orthernPlains

559

.0%;S

outhernPlains

564

.1%;P

acificCo

ast5

55.6%;S

outhwest5

87.5%.


TABLE

2Urina

ryBladd

erCan

cerf

Incide

nceby

Indian

Hea

lthSe

rviceReg

ionforAmerican

Indian

s/Alask

aNatives

andNon

-Hispa

nicWhites,U

nitedStates,1

999to

2004

CHSD

ACou

nties

AllC

ount

ies

IHSReg

ion

Sex

AI/A

N

Cou

nt

AI/A

N

Rateb

,c95

%CIfor

AI/A

NRate

NHW

Rate

RateRatio

c

(AI/AN

:NHW

)

95%

CIfor

RateRatio

AI/A

N

Cou

nt

AI/A

N

Rateb

,c95

%CIfor

AI/A

NRate

NHW

Rate

RateRatio

c

(AI/AN

:NHW

)

95%

CIfor

RateRatio

NorthernPlains

Both

sexes

9414

.811

.7-18.4

22.9

0.65

d0.51

-0.80

128

11.7

9.6-14

.123

.30.50

d0.41

-0.60

Male

7026

.820

.1-34.8

39.4

0.68

d0.51

-0.88

9320

.315

.8-25.6

41.2

0.49

d0.38

-0.62

Female

246.4

4.0-9.6

10.4

0.62

d0.39

-0.93

355.6

3.8-7.8

10.4

0.54

d0.37

-0.75

Alaska

eBo

thsexes

4513

.49.6-18

.126

.90.50

d0.35

-0.69

4513

.49.6-18

.126

.90.50

d0.35

-0.69

Male

3423

.015

.1-33.1

47.3

0.49

d0.31

-0.71

3423

.015

.1-33.1

47.3

0.49

d0.31

-0.71

Female

116.4

3.1-11

.38.6

0.74

0.34

-1.40

116.4

3.1-11

.38.6

0.74

d0.34

-1.40

Southe

rnPlains

Both

sexes

184

14.6

12.6-17.0

19.7

0.74

d0.64

-0.86

196

11.6

10.0-13.4

19.7

0.59

d0.50

-0.68

Male

132

25.0

20.6-29.9

35.0

0.71

d0.59

-0.86

141

19.5

16.2-23.2

35.2

0.55

d0.46

-0.66

Female

527.3

5.4-9.5

8.5

0.85

0.63

-1.13

555.8

4.4-7.6

8.3

0.70

d0.52

-0.91

Pacific

Coa

stBo

thsexes

103

8.6

6.9-10

.624

.00.36

d0.29

-0.44

133

6.2

5.2-7.5

23.8

0.26

d0.22

-0.31

Male

7514

.110

.8-18.0

42.0

0.34

d0.26

-0.43

9610

.18.0-12

.641

.80.24

d0.19

-0.30

Female

284.3

2.8-6.2

10.1

0.42

d0.27

-0.62

373.2

2.2-4.4

10.1

0.31

d0.22

-0.44

East

Both

sexes

3811

.98.3-16

.525

.80.46

d0.32

-0.64

131

6.3

5.2-7.5

24.6

0.26

d0.21

-0.31

Male

3022

.814

.6-33.4

44.7

0.51

d0.33

-0.75

9810

.98.6-13

.543

.00.25

d0.20

-0.31

Female

84.4

1.9-8.7

12.0

0.37

d0.15

-0.73

333.0

2.0-4.2

11.1

0.27

d0.18

-0.38

Southw

est

Both

sexes

543.2

2.4-4.2

23.8

0.13

d0.10

-0.18

603.2

2.4-4.2

22.6

0.14

d0.11

-0.19

Male

405.7

4.0-7.8

40.7

0.14

d0.10

-0.19

445.6

4.0-7.6

38.8

0.14

d0.10

-0.20

Female

141.4

0.7-2.3

10.1

0.14

d0.07

-0.23

161.5

0.8-2.4

9.7

0.15

d0.09

-0.25

Total

Both

sexes

518

9.6

8.8-10

.523

.90.40

d0.37

-0.44

693

7.6

7.0-8.2

23.7

0.32

d0.29

-0.34

Male

381

16.5

14.8-18.4

41.5

0.40

d0.36

-0.44

506

12.7

11.5-14.0

41.7

0.31

d0.28

-0.34

Female

137

4.5

3.8-5.3

10.5

0.43

d0.36

-0.51

187

3.7

3.2-4.3

10.6

0.35

d0.30

-0.41

Totaltrans

ition

alce

llBo

thsexes

452

8.3

7.6-9.2

22.2

0.38

d0.34

-0.41

615

6.7

6.1-7.2

22.1

0.30

d0.28

-0.33

Male

344

14.8

13.2-16.6

38.7

0.38

d0.34

-0.43

464

11.6

10.5-12.8

39.0

0.30

d0.27

-0.33

Female

108

3.5

2.9-4.3

9.5

0.37

d0.30

-0.45

151

3.0

2.5-3.5

9.6

0.31

d0.26

-0.36

Source

:Can

cerregistrie

sin

theNationa

lProgram

ofCa

ncer

Registrie

s(N

PCR)

oftheCe

ntersforDisea

seCo

ntrola

ndPrev

entio

nan

d/or

theSu

rveilla

nce,

Epidem

iology,a

ndEn

dRe

sults

(SEE

R)prog

ram

oftheNationa

lCan

cerInstitu

te;s

eeTa

ble1forstates

includ

ed.

CHSD

Aindica

tesCo

ntract

Hea

lthSe

rviceDeliveryAr

eas;

IHS,

Indian

Hea

lthSe

rvice;

AI/A

N,A

merican

Indian

s/Alaska

Natives;C

I,co

nfiden

ceinterval;N

HW,n

on-H

ispa

nicwhites.

aAI/A

Nrace

isrepo

rted

byNPC

Ran

dSE

ERregistrie

sor

throug

hlin

kage

with

theIH

Spa

tient

registratio

nda

taba

se.A

I/AN

person

sof

Hispa

nicorigin

areinclud

ed.

bRa

tesarepe

r10

0,00

0pe

rson

san

dareag

e-ad

justed

tothe20

00USstan

dard

popu

latio

n(19ag

egrou

ps,C

ensu

sP2

5-11

30).

cRa

teratio

sareca

lculated

inSE

ER*Statp

riorto

roun

ding

ofratesan

dmay

note

qual

RRca

lculated

from

ratespresen

tedin

thetable.

dRa

teratio

isstatistic

ally

sign

ifica

nt(P

<.05).

eRa

tesan

drate

ratio

sforAlaska

intheCH

SDAco

untie

ssectionarethesameas

thos

ein

theAllC

ountiessectionbe

caus

eallc

ountiesin

Alaska

areCH

SDAco

untie

s.f Insitu

andinva

sive

casesareinclud

ed.


TABLE

3Kidne

yPa

renc

hymaCan

cerIn

cide

nceRates

andRateRatios,

byAge

andIn

dian

Hea

lthSe

rviceReg

ionforAmerican

Indian

s/Alask

aNatives

andNon

-Hispa

nicWhites,

CHSD

ACou

nties,

UnitedStates,1

999to

2004

20-49Ye

ars

501

Years

AI/A

NNHW

AI/A

N:N

HW

AI/A

NNHW

AI/A

N:N

HW

IHSReg

ion

Sex

Cou

ntRatea

95%

CI

Cou

ntRatea

95%

CI

RRb

95%

CI

Cou

ntRatea

95%

CI

Cou

ntRatea

95%

CI

RRb

95%

CI

NorthernPlains

Both

sexes

458.6

6.3-11

.581

44.0

3.7-4.3

2.14

b1.55

-2.88

154

71.6

60.1-84.8

5,22

736

.635

.6-37.6

1.96

b1.64

-2.32

Male

259.9

6.4-14

.651

75.1

4.6-5.5

1.96

b1.26

-2.92

9087

.268

.8-109

.53,18

649

.647

.9-51.3

1.76

b1.38

-2.22

Female

207.3

4.5-11

.329

73.0

2.6-3.3

2.48

b1.49

-3.89

6457

.043

.4-73.7

2,04

125

.724

.6-26.9

2.22

b1.68

-2.88

Alaska

Both

sexes

114.3

2.2-7.7

513.6

2.7-4.8

1.20

0.56

-2.33

6663

.848

.8-82.1

202

39.7

34.0-46.2

1.61

b1.18

-2.17

Male

86.4

2.8-12

.630

4.0

2.7-5.8

1.59

0.63

-3.54

4392

.665

.0-128

.514

457

.947

.3-70.1

1.60

b1.07

-2.36

Female

�2.3

0.5-6.8

213.2

2.0-4.9

0.74

0.14

-2.45

2339

.724

.9-60.3

5823

.417

.5-30.7

1.69

0.98

-2.84

Southe

rnPlains

Both

sexes

618.4

6.4-10

.827

03.8

3.3-4.2

2.23

b1.66

-2.95

234

63.6

55.5-72.5

2,15

138

.236

.6-39.8

1.67

b1.45

-1.91

Male

349.7

6.7-13

.518

35.1

4.4-5.9

1.89

b1.27

-2.74

128

73.8

61.2-88.4

1,33

453

.350

.4-56.2

1.39

b1.14

-1.67

Female

277.2

4.7-10

.487

2.4

1.9-3.0

2.95

b1.84

-4.58

106

53.2

43.5-64.5

817

26.1

24.3-27.9

2.04

b1.65

-2.51

Pacific

Coa

stBo

thsexes

444.7

3.4-6.3

1,35

33.6

3.4-3.8

1.29

0.93

-1.74

119

34.2

27.9-41.4

9,05

034

.433

.7-35.1

0.99

0.81

-1.21

Male

275.8

3.8-8.5

870

4.6

4.3-5.0

1.25

0.82

-1.83

6843

.032

.4-56.0

5,76

848

.347

.0-49.5

0.89

0.67

-1.16

Female

173.6

2.1-5.7

483

2.6

2.4-2.9

1.37

0.79

-2.21

5127

.119

.9-36.1

3,28

222

.922

.1-23.7

1.19

0.87

-1.58

East

Both

sexes

94.2

1.9-8.0

980

4.1

3.9-4.4

1.03

0.47

-1.94

3739

.827

.6-55.7

7,20

438

.537

.6-39.4

1.04

0.72

-1.45

Male

�3.8

1.0-9.5

625

5.3

4.8-5.7

0.72

0.20

-1.82

1638

.620

.9-65.9

4,49

554

.753

.1-56.3

0.71

0.38

-1.21

Female

�4.7

1.5-10

.835

53.0

2.7-3.3

1.55

0.50

-3.63

2140

.925

.1-63.2

2,70

925

.524

.5-26.5

1.60

0.98

-2.48

Southw

est

Both

sexes

675.8

4.5-7.4

533

3.5

3.2-3.9

1.64

b1.25

-2.11

268

55.0

48.4-62.3

4,19

534

.133

.1-35.2

1.61

b1.41

-1.83

Male

386.8

4.8-9.4

323

4.3

3.8-4.7

1.61

b1.11

-2.25

165

79.4

67.2-93.1

2,67

547

.045

.2-48.8

1.69

b1.42

-1.99

Female

294.8

3.2-6.9

210

2.8

2.4-3.2

1.72

b1.12

-2.53

103

36.7

29.8-44.7

1,52

023

.222

.0-24.4

1.58

b1.28

-1.94

Total

Both

sexes

237

6.2

5.4-7.1

4,00

13.8

3.7-3.9

1.63

b1.42

-1.86

878

54.3

50.6-58.1

28,029

36.0

35.6-36.5

1.51

b1.40

-1.61

Male

136

7.4

6.2-8.7

2,54

84.8

4.6-5.0

1.52

b1.27

-1.81

510

69.9

63.5-76.7

17,602

50.2

49.4-50.9

1.39

1.27

-1.53

Female

101

5.1

4.2-6.2

1,45

32.8

2.7-2.9

1.84

b1.49

-2.25

368

41.6

37.4-46.2

10,427

24.4

23.9-24.8

1.71

b1.53

-1.90

TotalK

idne

yRC

CBo

thsexes

218

5.7

5.0-6.5

3,60

83.4

3.3-3.5

1.67

b1.45

-1.91

774

47.3

43.9-50.9

23,748

30.6

30.2-31.0

1.55

b1.43

-1.66

Male

128

6.9

5.8-8.3

2,29

44.4

4.2-4.5

1.60

b1.32

-1.91

446

60.4

54.6-66.7

15,058

42.7

42.0-43.4

1.41

b1.28

-1.56

Female

904.6

3.7-5.6

1,31

42.5

2.4-2.7

1.82

b1.45

-2.25

328

36.7

32.8-41.0

8,69

020

.520

.1-21.0

1.79

b1.59

-2.00

APC

APC

APC

APC

TotalK

idne

yAP

CBo

thsexes

237

3.0

28.0-15

.34,00

15.3c

3.1-7.6

878

3.3

22.4-9.3

28,029

3.2c

1.9-4.5

Male

136

5.9

27.6-21

.32,54

85.9c

2.7-9.2

510

3.2

24.8-11

.917

,602

3.0c

0.8-5.2

Female

101

20.4

214

.3-15.8

1,45

34.4c

0.1-8.9

368

3.1

24.4-11

.210

,427

3.5c

2.2-4.8

Source

:Can

cerregistrie

sin

theNationa

lProgram

ofCa

ncer

Registrie

sof

theCe

ntersforDisea

seCo

ntrola

ndPrev

entio

nan

d/or

theSu

rveilla

nce,

Epidem

iology,a

ndEn

dRe

sults

prog

ram

oftheNationa

lCan

cerInstitu

te;s

eeTa

ble1forstates

includ

ed.

CHSD

Aindica

tesCo

ntract

Hea

lthSe

rviceDeliveryAr

eas;

AI/A

N,A

merican

Indian

s/Alaska

Natives;N

HW,n

on-H

ispa

nicwhites;

IHS,

Indian

Hea

lthSe

rvice;

CI,c

onfid

ence

interval;R

R,rate

ratio

;APC

,ann

ualp

erce

ntag

ech

ange

.aRa

tesarepe

r10

0,00

0pe

rson

san

dareag

e-ad

justed

tothe20

00USstan

dard

popu

latio

n(19ag

egrou

ps,C

ensu

sP2

5-11

30).

bRa

teratio

isstatistic

ally

sign

ifica

nt(P

<.05).

cAP

Cis

statistic

ally

sign

ifica

nt(P

<.05).

~Co

unts

less

than

6aresu

ppressed

.


females of either age group. Among NHW females

aged 50 years and older, the increase was statistically

significant (3.5% per year). Among AI/AN aged 20

years to 49 years, bladder cancer incidence rates

were highest in the Northern Plains (3.3), Southern

Plains (2.4), and East (1.8) (Table 4). Among NHW

aged 20 years to 49 years, rates were highest in

Alaska (3.4) and the East (3.4). Among individuals

aged 50 years and older, the highest rates occurred

among NHW in Alaska (91.8). Incidence rates were

highest among AI/AN in the Southern Plains (49.2),

Northern Plains (48.2), and Alaska (46.1). Rate ratios

among individuals aged 50 years and older were all

significantly below 1, indicating significantly lower

incidence rates among AI/AN in all regions.

Regional Correlation of Incidence With Smokingand ObesityThe correlation between self-reported tobacco use

and bladder cancer incidence rates in CHSDA coun-

ties was statistically significant (r 5 0.9, P 5 .02) (Ta-

ble 5). The magnitude of this correlation for kidney

cancer incidence rates was not statistically significant

and less pronounced (r 5 0.5, P 5 .30), appearing

somewhat greater among AI/AN females (r 5 0.7, P

5 .15) than AI/AN males (r 5 0.4, P 5 .49). Correla-

tions between incidence and the prevalence of obe-

sity were not statistically significant (data not

shown).

Stage at DiagnosisAI/AN were significantly less likely to have been

diagnosed with earlier stages of cancer (in situ and

localized stage), including both bladder (76.3% vs

82.8%, P 5 .002) and kidney (51.9% vs 58.7%, P 5.001) cancer (Table 6). In addition, a higher propor-

tion of AI/AN were diagnosed with late-stage kidney

cancer compared with NHW (P 5 .026).

DISCUSSION

SummaryCompared with NHW, this study reports that kidney

parenchyma cancer incidence is approximately 1.5-

fold higher among AI/AN overall, and as great as 2.5-

fold higher among females in some regions. Tempo-

ral increases in kidney cancer incidence rates appear

to be comparable among AI/AN and NHW males,

although statistically significant only among NHW

males. Although bladder cancer incidence is signifi-

cantly lower among AI/AN compared with NHW,

there is substantial regional variation among AI/AN

alone, which correlates crudely with tobacco use. For

both cancer sites, AI/AN are less likely to be diag-

nosed with early-stage disease.

Kidney cancerHistologically, most kidney cancers (>80%) are renal

cell carcinomas (RCC), and therefore it is not surpris-

ing that differences between AI/AN and NHW were

similar for RCC compared with all cancers occurring

in the kidney.1 In most regions of the United States,

kidney cancer incidence rates were significantly

higher among AI/AN compared with NHW, and this

relationship was apparent in both younger and older

adult age groups. Smoking, obesity, and hypertension

together are estimated to account for approximately

50% to 60% of kidney cancers.1,20 Obesity alone is

attributed to approximately 25% of kidney cancers.21

AI/AN are more likely to be overweight and/or obese

than NHW.13,18,22-25 However, body mass index among

AI/AN does not vary as considerably as smoking by

region and did not explain well the regional differ-

ences observed among AI/AN in this study.18 Other

factors may be responsible for the 2-fold regional var-

iation in incidence among AI/AN. There is some evi-

dence that the use of diuretics may increase the risk

of kidney cancer in both hypertensive and normoten-

sive individuals.21,26-28 According to the Strong Heart

Study of American Indians in the United States, the

prevalence of the use of diuretics to treat hyperten-

sion among AI/AN may vary as much as 11% to 30%

by study region.29 However, the extent to which the

use of diuretics may contribute to regional variation

in kidney cancer incidence is not known.

A corollary condition to obesity is diabetes. Type

2 diabetes mellitus (‘‘diabetes’’) has been inconsis-

tently associated with an increased risk of RCC, and it

is possible that diabetes contributes to the etiology of

this cancer through increased risk of kidney failure

among diabetics. Studies among kidney dialysis

patients report an increased risk of kidney cancer.30,31

Kidney failure leading to dialysis is more prevalent

among AI/AN with diabetes and may be an important

kidney cancer risk factor among AI/AN.32,33 In addi-

tion, more recent research has focused on the impor-

tance of in utero exposures that may impact kidney

development and function.34 Two studies report that

children of mothers who were diabetic during preg-

nancy are more likely to have reduced diabetes con-

trol (ie, higher HbA1c) and a higher incidence of

kidney disease.35,36 Further research is needed to elu-

cidate the implications of these early life exposures

on later development of cancer.

Several other risk factors have been proposed,

including infections, diet, occupational exposures,

and family history.1,20,37 Approximately 4% of kidney


TABLE

4Urina

ryBladd

erCan

cera

Incide

nceRates

andRateRatios,

byAge

andIn

dian

Hea

lthSe

rviceReg

ionforAmerican

Indian

s/Alask

aNatives

andNon

-Hispa

nicWhites,

CHSD

ACou

nties,

UnitedStates,1

999to

2004

20-49Ye

ars

501

Years

AI/A

NNHW

AI/A

N:N

HW

AI/A

NNHW

AI/A

N:N

HW

IHSReg

ion

Cou

ntRateb

95%

CI

Cou

ntRateb

95%

CI

RRc

95%

CI

Cou

ntRateb

95%

CI

Cou

ntRateb

95%

CI

RRc

95%

CI

NorthernPlains

173.3

1.9-5.2

597

2.9

2.7-3.2

1.13

0.65

-1.81

7648

.237

.4-61.1

11,265

78.1

76.7-79.6

0.62

c0.48

-0.78

Alaska

�1.6

0.4-4.1

483.4

2.5-4.5

0.47

0.12

-1.28

4146

.132

.5-63.4

405

91.8

82.5-101

.80.50

c0.35

-0.70

Southe

rnPlains

182.4

1.4-3.8

214

2.9

2.6-3.4

0.82

0.48

-1.33

166

49.2

41.8-57.4

3,77

766

.664

.5-68.8

0.74

c0.63

-0.86

Pacific

Coa

st7

0.8

0.3-1.5

1,08

62.9

2.7-3.1

0.26

c0.10

-0.53

9630

.023

.9-37.2

21,723

82.1

81.0-83.2

0.37

c0.29

-0.45

East

�1.8

0.5-4.7

821

3.4

3.2-3.7

0.54

0.15

-1.37

3440

.227

.3-57.0

16,941

87.7

86.4-89.1

0.46

c0.31

-0.65

Southw

est

�0.2

0.0-0.7

436

2.9

2.6-3.2

0.08

c0.02

-0.24

5111

.28.2-14

.810

,017

81.4

79.8-83.0

0.14

c0.10

-0.18

TotalC

HSD

A53

1.4

1.0-1.8

3,20

23.0

2.9-3.1

0.45

c0.34

-0.60

464

32.6

29.6-35.8

64,128

81.5

80.9-82.1

0.40

c0.36

-0.44

Totalb

ladd

erTC

C44

1.1

0.8-1.5

2,95

72.8

2.7-2.9

0.41

c0.30

-0.55

407

28.3

25.5-31.4

59,531

75.7

75.1-76.3

0.37

c0.34

-0.41

APC

APC

APC

APC

Totalb

ladd

erAP

C53

216

.3d

225

.2-2

6.3

3,20

222.9

26.9-1.2

464

21.4

0.4-2

5.2

64,128

20.7d

20.9-20.4

Source

:Can

cerregistrie

sin

theNationa

lProgram

ofCa

ncer

Registrie

sof

theCe

ntersforDisea

seCo

ntrola

ndPrev

entio

nan

d/or

theSu

rveilla

nce,

Epidem

iology,a

ndEn

dRe

sults

prog

ram

oftheNationa

lCan

cerInstitu

te;s

eeTa

ble1forstates

includ

ed.

CHSD

Aindica

tesCo

ntract

Hea

lthSe

rviceDeliveryAr

eas;

AI/A

N,A

merican

Indian

s/Alaska

Natives;N

HW,n

on-H

ispa

nicwhites;

IHS,

Indian

Hea

lthSe

rvice;

CI,c

onfid

ence

interval;R

R,rate

ratio

;TCC

,trans

ition

alce

llca

rcinom

a;AP

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cancers diagnosed in the US are estimated to be

familial,38 and those diagnosed at earlier ages may be

more likely to have a genetic component,39 although

known familial kidney cancer syndromes have not

been described among AI/AN.38,40 Population-based

case-control studies suggest that multiple genetic and

environmental triggers are likely responsible.1

Recent increases in kidney cancer incidence rates

in the United States and abroad over the past few dec-

ades suggest that nongenetic factors are driving kid-

ney cancer trends.41,42 Among AI/AN, cancer of the

kidney is now the fourth most frequently diagnosed

cancer.1,2 The average annual increases in kidney can-

cer incidence among AI/AN and NHW over age 50

years in this study (3.0% to 3.5%) are comparable to

studies from earlier time periods reporting increases

of 1% to 3% annually.1,41,43 The 5.9% average annual

increase among younger adult NHW and AI/AN males

(aged 20 to 49 years) is of concern because of the

magnitude of the annual increase and the morbidity

of this cancer. However, this study involves a relatively

brief time period (6 years), which may or may not be

indicative of longer-term trends.

Kidney cancer incidence is generally 2-fold

higher among males than females.2 However, we

report that AI/AN females in some regions have inci-

dence rates closer to those of AI/AN males. Certain

exposures, including tobacco use and pregnancy, can

increase oxidative stress on the kidney, which may

be a common pathway increasing cancer risk.44 At

least 2 large cohort studies report an increased risk

of renal cell cancer among females with higher par-

ity, compared with nulliparous females.45,46 This sug-

gests that AI/AN females with higher parity may also

be at increased risk of kidney cancer.

Bladder cancerPrevious studies report lower bladder cancer inci-

dence and mortality among AI/AN than in other

populations.2,3,47 In the US, smoking is the major

risk factor for cancers of the bladder, and it may

account for approximately 70% of new bladder can-

cer cases among males and 20% to 30% among

females.20,48 In our study, among both males and

TABLE 6Urinary Bladdera and Kidney Parenchyma Cancer Incidence Rates and Percentage Distributions by Stageb and Indian Health Service Region forAmerican Indians/Alaska Natives and Non-Hispanic Whites, CHSDA Counties, United States, 2001 to 2003

Regional Distant Unstaged

Localized Race Count Ratec 95% CI

% of

Casesd Count Ratec 95% CI

% of

Casesd Count Ratec95%

CI

% of

Casesd Count Ratec95%

CI

% of

Casesd

Urinary

bladder AI/AN 200 7.1 6.1-8.2 76.3 23 0.8 0.5-1.3 8.6 12 0.4 0.2-0.8 4.3 23 0.9 0.6-1.4 9.7

NHW 27,929 19.7 19.4-19.9 82.8 2,611 1.8 1.8-1.9 7.6 1,063 0.7 0.7-0.8 2.9 2,200 1.5 1.5-1.6 6.3

P .002 .691 .123 .364

Kidney

parenchyma

AI/AN

310 9.4 8.4-10.6 51.9 83 2.5 1.9-3.1 13.8 130 4.0 3.3-4.8 22.1 62 2.1 1.6-2.8 11.6

NHW 9,665 7.1 6.9-7.2 58.7 2,597 1.9 1.8-1.9 15.7 3,015 2.2 2.1-2.2 18.2 1,471 1.0 1.0-1.1 8.3

P .001 .548 .026

Source: Cancer registries in the National Program of Cancer Registries of the Centers for Disease Control and Prevention and/or the Surveillance, Epidemiology, and End Results (SEER) program of the National

Cancer Institute; see Table 1 for states included.

CHSDA indicates Contract Health Service Delivery Areas; CI, confidence interval; AI/AN, American Indians/Alaska Natives; NHW, non-Hispanic whites.a In situ urinary bladder cases were included.b SEER Summary Stage 2000 was used.c Rates are per 100,000 persons and are age-adjusted to the 2000 US standard population (19 age groups, Census P25-1130).d Percentage stage distribution is age-adjusted to the 2000 US standard population; percentageages may not add to 100% due to rounding.

TABLE 5Regional Correlation of Cancer Incidence Rates (1999 to 2004) WithSelf-Reported Tobacco Use (BRFSS 2000 to 2006) Among AmericanIndian and Alaska Natives, CHSDA Counties, United States

Correlation Coefficient

Tobacco Use Urinary Bladdera (P) Kidney Parenchyma (P)

Both sexes .9 (.02) .5 (.30)

Male .9 (.01) .4 (.49)

Female .8 (.07) .7 (.15)

Source: Cancer registries in the National Program of Cancer Registries of the Centers for Disease

Control (CDC) and Prevention and the Surveillance, Epidemiology, and End Results program of the

National Cancer Institute (see Table 1 for states included); CDC’s BRFSS.

BRFSS indicates Behavioral Risk Factor Surveillance System; CHSDA, Contract Health Service Deliv-

ery Areas.a In situ and invasive cases are included.


females, approximately 90% of the regional variation

in bladder cancer among AI/AN was correlated with

tobacco use. The Behavioral Risk Factor Surveillance

System for years 2000 to 2006 reports higher smoking

prevalence among AI/AN in the Northern Plains

(40.1%), Alaska (39.4%), and the East (36.3%), regions

that also have higher bladder cancer incidence among

AI/AN.18 Consistent with this smoking pattern, Inuit

populations (Alaska, Canada, and Greenland) and

American Indians of the Northern Plains also have a

high incidence of lung cancer that exceeds rates

among NHW by 30% to 60%.3,49,50 Given the higher

incidence of lung cancer and higher prevalence of

smoking among AI/AN, the comparative deficit of

bladder cancer among AI/AN is somewhat enigmatic.

Further complicating this picture are other studies

that suggest that diabetes, again more prevalent

among AI/AN, may increase the risk of bladder can-

cer.51,52 These contrasting patterns suggest the need to

understand intervening factors that may affect the risk

of bladder cancer. Several case-control studies have

identified an elevated risk of bladder cancer among

certain occupations, including those in the rubber,

chemical, leather, metal, printing, painting, textile, and

truck driving industries. Occupational exposures

account for approximately 5% to 25% of bladder can-

cer cases among males and 8% to 11% among

females, although the proportion of AI/AN with expo-

sure to occupational bladder carcinogens is not

known.48

Other possible risks for bladder cancer include

family history, exposure to cyclophosphamide, ioniz-

ing radiation, arsenic, disinfection by-products con-

tained in chlorinated drinking water, and decreased

fluid intake.20 Individuals with a first primary bladder

cancer are at approximately 4-fold increased risk of a

secondary bladder cancer.37 Finally, there may be

molecular studies suggest important genes related to

bladder cancer susceptibility, although the preva-

lence of at-risk or protective genetic polymorphisms

among AI/AN populations is not known.53

Strengths and LimitationsStrengthsThis is the first study to identify broad regional pat-

terns of urologic cancers among the AI/AN population

on a national scale. Misclassification of AI/AN race

and ethnicity was reduced by linkage to the IHS

patient registration records and limiting the analysis

to CHSDA counties. Other statistics, such as survival

and stage at diagnosis, were similar in CHSDA and

non-CHSDA areas (data not presented here), suggest-

ing that the CHSDA areas provide a reasonable repre-

sentation of cancer cases, while at the same time

reducing misclassification of AI/AN race and ethnicity.

LimitationsIt is possible that regions with fewer reservation

land-based tribes, such as the East and Pacific Coast,

may have had greater misclassification of AI/AN race

and ethnicity than when compared with regions such

as the Northern Plains and Southwest, which would

result in lower than actual incidence rates among AI/

AN. For example, we did not observe an excess of

kidney cancer in these regions, whereas we did

observe an excess among AI/AN in all other regions.

Although AI/AN patients must return to a CHSDA to

become eligible for contract care services (eg, for

cancer treatment) through the Indian Health Service,

it is likely that a significant proportion do not. Efforts

to improve the classification of race and ethnicity in

these areas will still be important.

Our study could not account for increased medi-

cal surveillance in detecting cancer that may result

in a higher rate of case identification among some

individuals. For example, the assessment of certain

types of cancer—particularly multiple low-grade

bladder cancers—may be lower among AI/AN popu-

lations that reside in rural regions further from medi-

cal care. In addition, SEER summary staging

combines in situ and local-stage bladder cancer for

the staging systems used during the time period of

this study. It is possible that there are more subtle

differences in in situ versus invasive cancer stages

that could not be analyzed by this study.

ConclusionsOur study highlights major differences in bladder

and kidney cancer incidence rates between AI/AN

and NHW populations in the United States. AI/AN

have significantly higher kidney cancer incidence,

with recent increases evident for both AI/AN and

NHW. Despite the finding that bladder cancer inci-

dence among AI/AN is about half that of NHW, re-

gional incidence rates among AI/AN alone correlate

crudely with tobacco use. These results, combined

with the higher prevalence of late-stage bladder and

kidney cancers among AI/AN, emphasize the need

for sustained efforts to prevent smoking and reduce

obesity.

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