Lipoprotein alterations, abdominal fat distribution and breast cancer

Vol. 47, No. 4, April 1999 BIOCHEMISTRY andMOLECULAR BIOLOGY INTERNATIONAL pages 681-690

LIPOPROTEIN ALTERATIONS, ABDOMINAL FAT DISTRIBUTION A N D BREAST CANCER

Laura E. Schreier 1", Gabriela A. Berg 1, Francisco M, Basilio 2, Graciela I. Lopez ~, Alberto E. Etkin 2 and Regina L. Wikinski I

~ Laboratoly of Lipids and Lipoproteins, Dept. of Clinical Biochemistry-Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires

2Gynecology Service, Mammaly Pathology, Hospital C, G. Durand, Buenos Aires, Argentina

Received October 28, 1998

*To whom correspondence should be addressed: Lab. Lipidos y Lipoproteinas, Dept. Bioqt6mica Cllnica, Facuhad de Farmacia y Bioquimica, Universidad de Buenos Aires, lunin 956 (1113), Buenos Aires, Argentina.

S U M M A R Y Plasma lipid profile and abdominal obesity have been associated with breast cancer risk, however published resuits 'have been inconsistent. To clarify these associations we studied lipid and lipoprotein alterations, obesity degree and body fat distribution, in 30 newly diagnosed breast cancer patients without treatment and 30 controls matched by age and menopausal status. Both pre and postmenopausal breast cancer patients presented higher body mass index, waist/hip ratio and insulin levels than their matched controls. An increase in triglycerides and a decrease in HDL-cholesterol, especially in the HDLz subfraction, were observed in patients with breast cancer. Besides, HDL particle from these patients showed increased apo AJHDL-cholesterol ratio. These alterations were correlated with waist/hip ratio. The association between lipoprotein alterations and abdominal obesity independent of menopausal status, in untreated newly diagnosed breast cancer patients is reported for the first time in this study.

Key words: Breast Cancer, Lipids, Lipoproteins, Abdominal Obesity.

INTRODUCTION

There is a difference between the lipoprotein profiles described in patients with breast

cancer and those which appear in other types of cancer. Several studies carried out on

patients with other types of cancer have shown changes in the lipid levels and generally

associate hypocholesterolemia with tumors (1,2). There is no consistent information as

regards lipid and lipoprotein levels in breast cancer because studies are scarce and

contradictory.

Goodwin et at found elevated triglycerides in premenopausal breast cancer risk (3),

however, other authors have not found any connection between the increase in

triglycefides and breast cancer (2,4). The [5 and prel3 lipoproteins, which respectively

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Vo|. 47, No. 4, April 1999 BIOCHEMISTRY and MOLECULAR BIOLOGY INTERNATIONAL

correspond to LDL and VLDL, have been shown to be higher in women with newly

diagnosed breast cancer (5). Accordingly, Lane et aL (6) also found increased total,

LDL- and VLDL-cholesterol and apolipoprotein (apo) B, in newly diagnosed breast

cancer patients; they also proposed the increase in the apo A J B ratio, at the moment of

th e biopsy, as a good recurrence predictor.

Nevertheless the results about HDL plasma level are contradictory. While some

studies have associated breast cancer with an increase in HDL-cholesterol (7,8), others

reported a decrease (9), but all of them suggest that breast cancer is associated with

abnormalities in HDL-cholesterol levels (10).

On the other hand, there are controversies concerning obesity as a risk factor in breast

cancer (11,12). There is more agreement with respect to abdominal obesity distribution,

which is considered a risk factor for the development and prognosis of breast cancer

(11-13).

The relationship between breast cancer and abdominal fat distribution might explain

the lipoprotein alterations found in these patients. Metabolic factors and hormonal

alterations such as hyperinsulinemia associated with abdominal obesity are related to

lipoprotein metabolism and expressed partly as quantitative and qualitative alterations

of plasma lipoproteins (14,15).

The existing studies hardly evaluate those lipoprotein alterations in conjuction with the

abdominal obesity degree in patients with breast cancer. Moreover, several studies were

carried out on patients with risk of breast cancer, but very few on patients with

histological diagnosis of the disease. Besides, the menopausal status has been rarely

considered. Therefore, we examined the lipid and lipoprotein profile in patients with

breast cancer and related it with the obesity degree and body fat distribution.

MATERIAL AND METHODS

Patients and Controls:

We studied 60 women (28-72 years old) clinically examined in the service of Mammary Pathology, Gynecology Unit at C. G. Durand Hospital in Buenos Aires. We consecutively selected 30 patients and 30 healthy women as controls matched by age and menstrual or menopausal status. Breast cancer patients consulted the service due to the presence of a mammary nodule, detected by medical examination, self-examination or mammographic studies. Patients were included when presenting histologically proven breast cancer. Controls who referred to family history of breast cancer in mother or sister were not included. In beast cancer patients, as well as in controls, the menstrual

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Vol. 47, No. 4, April 1999 BIOCHEMISTRY and MOLECULAR BIOLOGY INTERNATIONAL

or menopausal status was diagnosed through the clinical-gynecological examination. Data about parity, alcohol consumption, diet and smoking habits and physical activity were recorded. Parity was similar among groups. In no case did alcohol consumption surpass 15 g/day and the diet was always varied. Five patients and 4 controls consumed 2 to 6 cigarettes per day and 5 patients smoked less than 6 cigarettes per day. The remaining patients and controls had been non-smokers for the last 10 years. The subjects were not under a regular training exeereise. None of the women were receiving chemotherapy or hormonal treatment, oral contraceptives or replacement therapy, nor hypolipidemic agents or any other drug that modifies the lipid metabolism. The cases that presented diabetes, renal, hepatic or tyroid disorders were excluded. Women whose weight had varied more than 5% in the last 6 months were also excluded.

The groups of patients and controls consisted of 15 premenopausal women and 15 postmenopausal ones each. All subjects gave their informed consent to participation.

Samples and Determinations The weight and height o f each patient and control were measured. The body mass

index (BMI) was calculated as weight (kg)/height (m) 2 to evaluate the obesity degree. The waist circumference was measured allowing 2,5 cm over the umbilicus line and

the hip circumference was measured on the maximum protrusion, both measurements were performed on a standing position. The waist/hip ratio was calculated and used as a marker of body fat distribution.

Blood samples were obtained after 12-h fast. In the case of patients with possible breast cancer diagnosis, the sample was obtained at least 5 days before the surgery, in order to avoid the influence of pre-surgical stress on the lipid profile. Breast cancer diagnosis was confn'med after surgery with the result of breast biopsies, establishing the definite inclusion of the patients.

Total cholesterol, triglycerides and glucose were determined in serum using standarized enzymatic methods (Boehringer-Mannheim, Germany) in a Hitachi 717 autoanalyser. LDL-cholesterol serum concentration was measured (16), within and between run precision (CV) were 4.7% and 5.0% respectively. The measurements of total HDL-cholesterol and its subfractions HDL 2 and HDL 3 were performed by methods of selective precipitation (17), within run and between day precision (CV) were 3.2% and. 3.8% for total HDL-cholesterol and 5.4% and 6.8% for HDL3-cholesterol, respectively. Apo A 1 and apo B were determined by electroimmunodiffusion (18), within ran and between day precision (CV) were 3.7% and 4.0% for apoA 1 and 3.1% and 4.0% for apoB, respectively. Insulin was measured in serum using Microparticle Enzyme Immunoassay (MEIA, Abbott- IMx) within run precision, CV: 2.1% and between day precision, CV: 3.0%.

Statistical Analysis Differences between groups were tested using Student test for independent samples or

Mann-Whitney U-Test for skewed data. The correlation between different variables was performed by linear regression according to Pearson. Values of p<0.05 were considered significant.

RESULTS

Table 1 shows the values o f triglycerides, total cholesterol, LDL-cholesterol and apo B

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determined in serum of breast cancer patients and controls, and reflects an increase in

the concentration of triglycerides, both in pre and postmenopausal breast cancer

patients. There was no difference in total cholesterol, LDL-cholesterol and apo B

concentration between patients and controls. In turn, postmenopansal women, both

breast cancer and controls, showed higher levels of total and LDL cholesterol,

triglycerides than premenopausal ones.

TABLE 1: Trigtyceride, total cholesterol, LDL-cholesterol and apolipoprotein B plasma concentration in newly diagnosed breast cancer patients and controls. Both groups were subdivided in premenopausal (Pre-M) and postmenopausal (Post-M) women. Values are mean (SEM), expressed in mg/dl.

n Triglyeerides

Patients 30 127 "(7.5)

Pre-M 15 111 b (9.8)

Post-M 15 141r

Controls 30 88 (5.3)

Pre-M 15 71 (5.9)

Post-M 15 105 (6.5)

Cholesterol Apol ipoprotein B total LDL 217 (8.1) 138 (8.3)

197 (11.1) l l 9 ( l l . t )

232~(11.0) 153~(11.1)

236 (7.l) 145 (7.5)

214 (8.3) 125 (8.2)

259~(8.5) 165~(10.6)

134 (4.9)

120 (6.5)

147 c (5.8)

125 (7.6)

117 (12.5)

133 (9.0)

a p < 0,001 v s controls b p < 0.01 v s controls Pre-M c p < 0.05 v s Breast Cancer Pre-M d p < 0.01 v s controls Post-M e p < 0.05 v s controls Pre-M

The level of total HDL-cholesterol and its subfractions HDL 2 and HDL 3 was lower

both in post and premenopausal women with breast cancer than in their matched

controls (Table 2). HDL-cholesterol decreased at the expense of the HDL2 fraction,

which was considerably lower (- 41%) as compared to HDL 3 (- 8%). There was no

difference with respect to apo A1 (Table 2), however apoA1/HDL-cholesterol ratio was

higher in breast cancer patients (2.86:50.12) than in controls (2.09:k0.08), p<0.001.

Breast cancer women had higher BMI than controls, in premenopausal as well as in

postmenopausal women (Figure l-A). But it is important to point out that the difference

regarding the waist/hip ratio within both groups was much greater (Fig.l-B). On the

other hand, postmenopansal groups, with or without breast cancer, had higher BMI and

waist/hip ratio than premenopausal ones.

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TABLE 2: Plasma concentration of HDL-cholesterol, its subfraction HDL2 and HDL 3 and apolipoprotein A l in newly diagnosed breast cancer patients and controls. Both groups were subdivided in premenopausal (Pre-M) and postmenopansal (Post-M) women. Values are mean (SEM), expressed in mg/dl.

n HDL-Cholesterol Total HDL z HDL s

Patients 30 56 a (2.8) 9.9" (1.8) 46.1 ~ (2.3)

Pre-M 15 57 b (4.9) 12.3 b (3.1) 44.7 (3.4)

Post-M 15 55 c (3.0) 7.0 r (1.0) 48,0 c (3.0)

Controls 30 73 (2.1} 16.7 (1.7) 56.3 (1.8)

Pre-M 15 72 (3.3) t9.8 (2.5) 52.2 (2.3)

Post-M 15 73 (2.9) 13.5 (2.3) 59,5 (2.5)

a p < 0.01 vs controls b p < 0.05 vs controls Pre-M c p < 0.01 vs controls Post-M

Al~olipoprotein A t

153 (4.8) 147 (6.9)

157 (6.6)

149 (5.3) t54 (8.0) 145 (7.0)

Elevated triglycerides, decreased HDL-cholesterol and increased apoAJHDL-

cholesterol, were significantly correlated with the waist/hip ratio (Figure 2).

Fasting insulin values were higher in breast cancer patients, 90th percentile: 15.9

gUI/ml and range: 3.8-17.1 gUI/ml, than in controls, 90th: 8.9 ~tUI/ml and range 3.0-9.9

gUI/ml, p<0.01. However, glycemia was similar and within normal range: 69-102 mg/dl

in controls and 70-99 mg/dl in breast cancer patients.

DISCUSSION

Newly diagnosed untreated breast cancer patients showed higher triglyceride and

lower HDL-cholesterol concentrations, the latter was due to a reduction in HDL2

fraction in comparison to matched controls. Furthermore, breast cancer patients revealed

higher obesity degree and fat localization in the abdominal region independent of their

menopausal status. The increase in triglyceride, the decrease in HDL-cholesterol levels

and the increased in apo At/HDL-cholesterol ratio, were associated with the increase in

waist/hip ratio.

The lipid and lipoprotein variations that normally occur with the increase of age and

menopausal status, were foreseen in the design of this study by chosing age- and

menopausal status-matched controls. In agreement with their age, postmenopausal

women showed an increase in total and LDL-chotesterol with respect to each

premenopausal group. However, the independent analysis of pre and postmenopausal

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woman subgroups showed that abdominal obesity and lipoprotein alterations, observed

in both postmenopausal subgroups, also existed in prernenopausal breast cancer

patients.

10

35

30

25

~ 20

Premenopausal Postmenopausal

A) I ~ Patients w th } breast cancer I [3 Controls !

B) 1

0.9

0.8

0.7 E 0 . 6

0.5 -7 0.4

~ 0.:3

0.2 0.1

Premenopausat

d T

Poslm~mopausal

m Paden~s~with~ breast cancer I

[] Controls / [ A

a: p < 0.05 vs postmenopausal patients b: p < 0.05 vs postmenopausal controls c: p < 0.01 vs premenopausal controls d: p < 0.01 vs postmenopausal controls

FIGURE 1: A) Body mass index (Kg/m 2) in pre and postmenopausal breast cancer patients and matched controls. Bars represent mean values-a:SEM. Each premertopausal group has n=t 5, each postmenopausal group has n = 15.

B) Waist/hip ratio (em/em) in pre and postmenopausal breast cancer patients and matched controls. Bars represent mean valuesa:SEM. Each premenopausal group has n= 15, each postmenopausal group has n = 15.

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250,

200,

150

100

50

0 0,6

y = 279x - 110,62 r~0,55; 11=60

p<0,01

- - j

- ~ - ~ . = ~ ~

I I i # I I I I

0,65 0,7 0,75 0,8 0,85 0,9 0,95 1

WAIST/HIP (era/era)

100.

80.

6 0

4 0

2 0

0 0,6

4,5 - 4,0- 3,5- 3,0-

=o 2 . S

2,0.

~ 1,5. ~. 1,o.

0,5 0,0

0,6

y = -t04,67X 4-146,36 _" " = r=O,SO; n=60

p<0,01

~ o ~ �9 " - - - - - ~

i i I i I I I I

0,65 0,7 0,75 0,8 0,85 0,9 0,95 1

WAIST/HIP (cngcm)

y = 4,665x - 1,1262 r=-0,52; n=60

p<0,01 = =

i , i i i i ~ 1 i

0.65 0,7 0,75 0,5 0,85 0,9 0,95 1

WAIST/HIP (cm/cm)

FIGURE 2: Correlation b e t w e e n w a i s t / h i p r a t i o a n d : A) Triglyceride concentration; B) HDL-cholesterol concentration and C) apolipoprotein (Apo) AI/HDL-claolesterol (chol) ratio, in p a t i e n t s a n d controls.

Although some studies showed controversial results with respect to the association

between generalized obesity and breast cancer development, when we focused the

analysis on fat distribution, the relationship between abdominal obesity and breast

687


cancer risk became more evident, as it has already been suggested by other authors

(12,19).

Some authors have also found higher triglyceride levels in breast cancer patients

(3,7,9,20). Endocrine-metabolic alterations linked to abdominal obesity and, possibly, to

breast cancer have probably contributed to the increase in triglycerides in women with

breast cancer. We consider that the increase in triglycerides is due in part to higher

insulin levels, BMI and waist/hip ratio found in our breast cancer patients. The

significant and positive correlation between triglyceride plasma concentration and

waist/hip ratio reveals the association between triglycerides and abdominal obesity in

breast cancer

The lower HDL-cholesterol level in patients with breast cancer is compatible with the

higher concentration of triglycerides (21). In turn, the decrease in HDL-cholesterol,

specially in HDL 2, would be related to the body fat distribution, as it has been already

described (15). The significant correlation obtained between the increase in waist/hip

ratio and the decrease in HDL-cholesterol, supports the previous idea. Moreover, an

alteration was found in the HDL particle, being relatively richer in apo AI and poorer in

cholesterol The positive correlation between the waist/hip and the apo AJHDL-

cholesterol ratios suggests that atypic ttDL particle is related to the abdominal obesity

degree.

An important cohort study carried out by Hoyer and Engholm (22) showed an inverse

relation between HDL-cholesterol and breast cancer risk, association which was not

modified after adjustment by factors such as age, menarche, menopause, BMI and

alcohol consumption. Others (23), also found lower HDL-cholesterol levels in women

with breast cancer, as compared to women that suffered from uterine cervix cancer and

to healthy controls. Nevertheless, these results and ours do not agree with those of other

authors who suggest a direct relationship between HDL-cholesterol levels and breast

cancer risk (7) or with those who do not find any relationship between this risk and

HDL-cholesterol, among other lipid parameters (4).

Moreover, abdominal obesity is associated with hyperinsulinemia, which occurs

mainly as a result of the state of insulin resistance (14). The association betwen insulin

resistance and breast cancer has already been reported (24). Insulin resistance generates

modifications in plasma lipoproteins, specially a triglyceride increase and HDL-

cholesterol decrease (15).

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It is important to add that diets rich in saturated fat possibly constitute a risk factor for

breast cancer, mainly in the subgroups with greater risk (25). Nevertheless, it is difficult

to evaluate real fat consumption in diets and this would be due to the fact that the

methods used are not highly reliable. Therefore, there are no results which demonstrate

the direct association between saturated fat intake and breast cancer, though the effect of

this diet on the lipid profile is widely known (26). Kumar et al, (27) found some lipid

alterations similar to those shown in this study, nonetheless, they assume that the

alterations are mainly a consequence of diet habits, minimizing metabolic and hormonal

factors.

It must be highlighted that the exposed results belong to a group of untreated newly

diagnosed breast cancer patients, without history of hormonal treatments, matched to

controls of similar age and menopausal status. This study contributes to a better

understanding of this specific stage of the disease.

It must still be proven whether the association between plasma lipoprotein metabolism

and breast cancer development have direct or indirect relationship with abdominal

obesity and hormonal alterations.

Acknowledgments: This study was carried out thank to the grant from University of Buenos Aires, n ~ FA 085

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Lipoprotein alterations, abdominal fat distribution and breast cancer

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