The association between breast cancer and diet and other factors

Association of Dyslipidemia, Increased Insulin Resistance, and Serum CA 15-3 with Increased Risk of Breast Cancer in Urban Areas of North and Central India

Objective:

This study aims to determine the association of dyslipidemia and increased insulin resistance (IR) with increased breast cancer (BC) risk.

Materials and Methods:

The study group comprised 110 premenopausal and 143 postmenopausal, untreated female BC patients in the age range of 29–72 years. Control group consisted of 117 premenopausal and 141 postmenopausal healthy females in the age range of 23–75. Approximately 8-ml blood samples were drawn to measure various biochemical parameters. Serum glucose, total cholesterol, triglyceride (TG), and high-density lipoprotein-cholesterol were measured. Very low-density lipoprotein-cholesterol (VLDL-C) and LDL-C were calculated using Friedewald's formula. Serum insulin and serum CA 15-3 were estimated by immune enzymatic assay. IR was assessed using homeostasis model assessment IR index (HOMA-IR).

Results:

Clinical variables in the case and control groups were compared using the unpaired Student's t-test. The crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by binary logistic regression analysis. Pearson's correlation analysis was used to determine the association between CA 15-3 and variables of interest. Total cholesterol, TG, LDL, VLDL, serum glucose, serum insulin, HOMA-IR, and serum CA 15-3 were significantly higher (P < 0.001) in BC patients compared to those in controls. Significant adjusted ORs with 95% CI were found to be fasting glucose, total cholesterol, and TGs. We also found a significant positive correlation between total cholesterol, TG, LDL, serum glucose, serum insulin, HOMA-IR, and serum CA 15-3.

Conclusion:

This study confirms the association between dyslipidemia, IR, and increased BC risk.

Assessment of biochemical profiles in premenopausal and postmenopausal women with breast cancer

OBJECTIVE

The study was conducted to assess biochemical profiles in premenopausal and postmenopausal women having breast cancer.

MATERIALS AND METHODS

A hospital based case control study was carried out at Manipal Teaching Hospital (MTH), Pokhara, Nepal. The analysed variables were age, metabolic profile including total cholesterol, triglycerides, HDL-C, LDL-C, blood sugar, insulin concentration, C-peptide, HbA1c and selenium. Descriptive statistics and testing of hypothesis were used for the analysis using EPI INFO and SPSS 16 software.

RESULTS

In premenopausal women, significant differences were noted for total cholesterol (P value <0.001), triglycerides (P value 0.002), HbA1c level (P value <0.001), insulin concentration (P value 0.030), C-peptide concentration (P value 0.001), and selenium (P value <0.001) between cases and controls. Insignificant results were found for HDL-C (P value 0.749), LDL-C (P value 0.933), blood sugar (P value 0.59) and BMI (P value 0.746). Similarly, significant difference in total cholesterol (P value <0.001), triglycerides (P value 0.001), LDL-C (P value <0.001), HDL-C (P value 0.025), blood sugar (P value <0.001), insulin concentration (P value <0.001), c-peptide concentration (P value <0.001), HbA1c level (P value <0.001) and selenium (P value <0.001) were observed for postmenopausal patients and controls.

CONCLUSIONS

Assessing metabolic changes and their management may be important for control of breast cancer and increased survival.

Status of epidermal growth factor receptors family in hormone-dependent carcinomas of the breast and prostate with reference to serum lipids and lipoproteins

There are numerous growing evidences of resemblance between carcinomas of the breast and prostate. A total of 45 cases of these two hormone-dependent cancers along with appropriate controls were subjected for status of epidermal growth factor receptors as well as serum lipid profile. Paraffin embedded tissue sections from aforesald tumours were analysed by immunohistochemical staining for epidermal growth factor receptor (EGF-R), c-erbB-2 oncoprotein, estrogen receptor (ER) and progesterone receptor (PgR). Sera from same individuals were studied for serum lipid profile analysis. The study revealed that immunoexpression of all receptor proteins (EGF-R). c-erbB-2 was significantly higher in breast carcinoma. In addition, mean levels of triglycerides, total cholesterol, LDL-cholesterol were found to be significantly elevated while the level of HDL-cholesterol was observed to be lower among patients with breast cancer as compared to matched controls. Further, ER-positive breast cancer cases have significantly higher mean level of HDL-cholesterol when compared with ER-negative breast cancer patients. Contrary to this, no alteration in different serum lipid fractions was noticed among the patients with prostate cancer. However, a positive relationship was noticed between immunoexpressions of EGF-R and c-erbB-2 in prostate cancer.

Retinol, vitamins A, C, and E and breast cancer risk: a meta-analysis and meta-regression

OBJECTIVE

To comprehensively summarize the associations between retinol, vitamins A, C, and E and breast cancer, and quantitatively estimate their dose-response relationships.

METHODS

We searched PubMed, Embase, and Cochrane databases (from January 1982 to 15 March 2011) and the references of the relevant articles in English with sufficient information to estimate relative risk or odds ratio and the 95% confidence intervals, and comparable categories of vitamins. Two reviewers independently extracted data using a standardized form, with any discrepancy adjudicated by the third reviewer.

RESULTS

Overall, 51 studies met the inclusion criteria. Comparing the highest with the lowest intake, total vitamin A intake reduced the breast cancer risk by 17% (pooled OR = 0.83, 95% CI: 0.78-0.88). Further subgroup analysis based on study design did not change the significant reduction. Although the dietary vitamin A, dietary vitamin E, and total vitamin E intake all reduced breast cancer risk significantly when data from all studies were pooled, the results became nonsignificant when data from cohort studies were pooled. The significant association between total retinol intake and breast cancer in all studies became nonsignificant in case-control studies but remain significant in cohort studies. No significant dose-response relationship was observed in the higher intake of these vitamins with reduced breast cancer risk.

CONCLUSIONS

Our results indicate that both the total intake of vitamin A and retinol could reduce breast cancer risk. However, associations between other vitamins and breast cancer seem to be limited.

A population-based cohort study of HRT use and breast cancer in Korea

The incidence of breast cancer has recently been ranked first in Korea. This is a population-based cohort study that aims to evaluate the risk of breast cancer from the use of hormone replacement therapy (HRT). A total of 9579 participants were observed between January 1998 and June 2004; 6108 women who took HRT constituted the HRT group, and 3471 women who did not take HRT constituted the non-HRT group. Using the database from the Korea Central Cancer Registry, the authors examined the incidence of breast cancer from HRT. A total of 26 cases of breast cancer developed in the HRT group as compared with the 13 cases in the non-HRT group, during the follow-up period. The relative risk of developing breast cancer in the HRT group was 1.16 times higher than in the non-HRT group, with a population attributable risk of 29.9%. The risk of breast cancer in the HRT group increased when the risk factors were adjusted in the model.

Serum lipid profile of breast cancer patients

The purpose of this study was to carry out a comparative study to investigate the effect of lipid profile, oestradiol and obesity on the risk of a woman developing breast cancer. This study was carried out at the Komfo Anokye Teaching Hospital (KATH), Peace and Love Hospital, Oduom, Kumasi and Redeemed Clinic, Nima, Accra between May 2002 and March 2003. In this study, 200 consented women comprising 100 breast cancer patients (43 pre- and 57 post-menopausal) and 100 controls (45 pre- and 55 post-menopausal) with similar age range (25 to 80 years) were assessed for lipid profile, oestradiol and BMI. There was a significant increase in Body Mass Index (BMI) (p = 0.011), Total Cholesterol (TC) (p < 0.001), triglyceride (p = 0.026) and low density lipoprotein (LDL-cholesterol) (p = 0.001) of the breast cancer patients compared to the controls. With the exception of oestradiol (EST) that decreased, the lipid profile generally increased with age in both subjects and controls with the subjects having a much higher value than the corresponding control. There was also a significant positive correlation between BMI and TC (r2 = 0.022; p = 0.002) and also between BMI and LDL-cholesterol (r2 = 0.031; p = 0.0003). Apart from EST and LDL-cholesterol that were increased significantly only in the postmenopausal phase in comparison to the controls, BMI, TC and TG were increased in both pre-menopausal and post menopausal phases with HDL-cholesterol remaining unchanged. This study confirms the association between dyslipidaemia, BMI and increased breast cancer risk.

Results based on 124 cases of breast cancer and 97 controls from Taiwan suggest that the single nucleotide polymorphism (SNP309) in the MDM2 gene promoter is associated with earlier onset and increased risk of breast cancer

Background

It has been suggested that the single nucleotide polymorphism 309 (SNP309, T -> G) in the promoter region of the MDM2 gene is important for tumor development; however, with regards to breast cancer, inconsistent associations have been reported worldwide. It is speculated that these conflicting results may have arisen due to different patient subgroups and ethnicities studied. For the first time, this study explores the effect of the MDM2 SNP309 genotype on Taiwanese breast cancer patients.

Methods

Genomic DNA was obtained from the whole blood of 124 breast cancer patients and 97 cancer-free healthy women living in Taiwan. MDM2 SNP309 genotyping was carried out by restriction fragment length polymorphism (RFLP) assay. The multivariate logistic regression and the Kaplan-Meier method were used for analyzing the risk association and significance of age at diagnosis among different MDM2 SNP309 genotypes, respectively.

Results

Compared to the TT genotype, an increased risk association with breast cancer was apparent for the GG genotype (OR = 3.05, 95% CI = 1.04 to 8.95), and for the TG genotype (OR = 2.12, 95% CI = 0.90 to 5.00) after adjusting for age, cardiovascular disease/diabetes, oral contraceptive usage, and body mass index, which exhibits significant difference between cases and controls. Furthermore, the average ages at diagnosis for breast cancer patients were 53.6, 52 and 47 years for those harboring TT, TG and GG genotypes, respectively. A significant difference in median age of onset for breast cancer between GG and TT+TG genotypes was obtained by the log-rank test (p = 0.0067).

Conclusion

Findings based on the current sample size suggest that the MDM2 SNP309 GG genotype may be associated with both the risk of breast cancer and an earlier age of onset in Taiwanese women.

Serum selenium level and other risk factors for breast cancer among patients in a Malaysian hospital

OBJECTIVE

The aim of this study is to investigate the association between breast cancer and serum selenium level as well as other risk factors for breast cancer.

METHODS

A matched case-control study was conducted in a hospital in Malaysia from July 2000 to January 2001 and from May 2001 to June 2001. Sixty-two newly diagnosed breast cancer patients were selected as the cases. Each control, selected from the same hospital population was matched to each case according to age, ethnic group, and menopausal status.

RESULTS

The mean selenium concentration among the cases was significantly lower than that among the control. There was a significant association (p<0.05) between breast cancer and low selenium serum level, nulliparity (OR=5.5,95% CI=1.22 to 24.81), exposure to cigarette smoke (OR=2.2, 95% CI=1.04 to 4.65) and use of oral contraceptives (OR=3.0, 95% CI=1.09 to 8.25) as determined by the McNemar test. Multivariate analysis showed that nulliparity (OR=10.08, 95% CI=1.48 to 68.52) and use of oral contraceptives (OR=3.66, 95% CI=1.36 to 9.87) were associated with increased breast cancer risk. An increased selenium concentration contributes to a reduced risk of breast cancer (OR=0.89, 95% CI=0.84 to 0.94).

CONCLUSION

The results suggest that use of oral contraceptive pills, being nulliparous, and a low serum selenium level are associated with breast cancer.

Dietary Fat and Postmenopausal Invasive Breast Cancer in the National Institutes of Health-AARP Diet and Health Study Cohort

BACKGROUND

Although ecologic association and animal studies support a direct effect of dietary fat on the development of breast cancer, results of epidemiologic studies have been inconclusive.

METHODS

We prospectively analyzed the association between fat consumption and the incidence of postmenopausal invasive breast cancer in the National Institutes of Health-AARP Diet and Health Study, a US cohort comprising 188,736 postmenopausal women who completed a 124-item food-frequency questionnaire in 1995-1996. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression models with adjustment for energy and potential confounding factors. All statistical tests were two-sided.

RESULTS

Over an average follow-up of 4.4 years, the cohort yielded 3501 cases of invasive breast cancer. The hazard ratio of breast cancer for the highest (median intake, 40.1% energy from total fat; 434 cases per 100,000 person-years) versus the lowest (median intake, 20.3% energy from total fat; 392 cases per 100,000 person-years) quintile of total fat intake was 1.11 (95% CI = 1.00 to 1.24; P(trend) = .017). The corresponding hazard ratio for a twofold increase in percent energy from total fat on the continuous scale was 1.15 (95% CI = 1.05 to 1.26). Positive associations were also found for subtypes of fat (hazard ratio for a twofold increase in percent energy from saturated fat = 1.13; 95% CI = 1.05 to 1.22; from monounsaturated fat, HR = 1.12; 95% CI = 1.03 to 1.21; from polyunsaturated fat, HR = 1.10, 95% CI = 1.01 to 1.20). Correction for measurement error in nutrient intakes, on the basis of a calibration substudy that used two 24-hour dietary recalls, strengthened the associations, yielding an estimated hazard ratio for total fat of 1.32 (95% CI = 1.11 to 1.58). Secondary analyses showed that associations between total, saturated, and monounsaturated fat intakes were confined to women who were not using menopausal hormone therapy at baseline.

CONCLUSION

In this large prospective cohort with a wide range of fat intake, dietary fat intake was directly associated with the risk of postmenopausal invasive breast cancer.

Fruit and vegetables in cancer prevention

Our aim was to review the epidemiological literature on possible cancer-preventive effects of the consumption of fruits and vegetables in humans, to quantify the effect of high versus low consumption of fruits and vegetables, and to give an overall assessment of the existing evidence. We based our work on an expert meeting conducted by the International Agency for Research on Cancer in 2003. A qualitative reading and evaluation of relevant articles on the cancer-preventive effect of the consumption of fruits and vegetables was made followed by the calculation of the mean relative risk and range for cohort and case-control studies separately. The possible population-preventable fraction for modifying diet in relation to fruit and vegetable consumption was calculated as well as an overall statement about the degree of evidence for the cancer-preventive effect of fruit and vegetable consumption for each cancer site. There is limited evidence for a cancer-preventive effect of the consumption of fruits and vegetables for cancer of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of the consumption of fruits and vegetables for all other sites. Applying this range of risk difference to the range of prevalence of low intake, the preventable fraction for low fruit and vegetable intake would fall into the range of 5-12%. It is important to recognize that this is only a crude range of estimates and that the proportion of cancers that might be preventable by increasing fruit and vegetable intake may vary beyond this range for specific cancer sites and across different regions of the world.

Food and Botanical Groupings and Risk of Breast Cancer: A Case-Control Study in Shanghai, China

Breast cancer incidence rates more than double in Chinese women as they migrate from China to Hong Kong to the United States, suggesting that environmental factors contribute to the international variation in breast cancer incidence. Several dietary factors, which differ between the United States and the Chinese population, including intake of soy, meat, and fruits and vegetables, have been suggested to affect breast cancer risk. This report describes results from a case-control study of diet and risk of breast cancer nested in a randomized trial of breast self exam in Shanghai, China. Participating breast cancer cases (n = 378) and frequency age-matched controls (n = 1,070) completed a comprehensive food frequency questionnaire and a risk factor questionnaire. After adjustment for age, total energy intake, and total years of breast-feeding, women in the highest quartile of fruit and vegetable intake (≥3.8 servings/d) were significantly less likely to have breast cancer (odds ratio, 0.48; 95% confidence interval, 0.29-0.78) as compared with women in the lowest quartile of intake (≤2.3 servings/d). Egg consumption was also significantly inversely associated with risk of breast cancer (odds ratio for ≥6.0 eggs/wk versus ≤2.0 eggs/wk is 0.56; 95% confidence interval, 0.35-0.91). There was no difference in soy consumption between cases and controls. None of the associations with a single botanical family explained the strong inverse relationship between fruits and vegetables and breast cancer risk. These results provide additional evidence in support of the important role of fruits and vegetables in breast cancer prevention.

Improvement of metabolism among obese breast cancer survivors in differing weight loss regimens

OBJECTIVE

To compare the efficacy of different weight loss regimens on body weight loss and metabolic improvement in breast cancer survivors.

RESEARCH METHODS AND PROCEDURES

Forty-eight obese breast cancer survivors were randomly divided into four groups and were followed for 1 year: 1) the Control group (subjects did not receive specific nutrition counseling); 2) the Weight Watchers group (subjects were given free coupons to attend weekly Weight Watchers meetings); 3) the Individualized group (a registered dietitian provided one-on-one nutritional counseling); and 4) the Comprehensive group (subjects received individualized dietary counseling and free coupons for the weekly Weight Watchers meetings). At baseline and 3-, 6-, and 12-month data collection visits, a fasting blood sample was obtained for assays. A three-day dietary record was kept during the week before these visits and dietary intake was analyzed.

RESULTS

Subjects in the three intervention groups lost weight (Control: 1.1 +/- 1.7 kg; Weight Watchers: -2.7 +/- 2.1 kg; Individualized: -8.0 +/- 1.9 kg; Comprehensive: -9.5 +/- 2.7 kg) and percentage body fat, but only the Individualized and Comprehensive groups had significant losses. Subjects in the Comprehensive group showed the most improvement in cholesterol levels and had reductions in blood leptin levels.

DISCUSSION

Because insulin resistance and high blood leptin levels are associated with breast cancer, losing weight to improve these parameters may reduce the risk of recurrence. Only subjects in the Comprehensive group showed significant reductions in body weight and fat, energy intake, and leptin levels. For breast cancer survivors, different weight loss strategies should be considered to assist them in losing weight.

Epidemiologic evidence of the protective effect of fruit and vegetables on cancer risk

BACKGROUND

Diets rich in fruit and vegetables have been recommended for preventing cancer. The evidence supporting this recommendation is based on observational studies, although results of several prospective studies have cast some doubts on whether fruit and vegetables are associated with cancer risk reduction.

OBJECTIVE

We sought to summarize evidence from case-control and prospective studies on fruit and vegetable intake and cancer risk with a meta-analytic approach.

DESIGN

Published case-control and cohort studies that reported on total vegetable and fruit intake and risk of cancer of several sites were included. Relative risks were estimated by using linear logistic regression models.

RESULTS

Case-control studies overall support a significant reduction in the risks of cancers of the esophagus, lung, stomach, and colorectum associated with both fruit and vegetables; breast cancer is associated with vegetables but not with fruit; and bladder cancer is associated with fruit but not with vegetables. The overall relative risk estimates from cohort studies suggest a protective effect of both fruit and vegetables for most cancer sites considered, but the risk reduction is significant only for cancers of the lung and bladder and only for fruit.

CONCLUSIONS

Prospective studies provide weaker evidence than do case-control studies of the association of fruit and vegetable consumption with reduced cancer risk. The discrepancies may be related to recall and selection biases in case-control studies. In contrast, the association may have been underestimated in prospective studies because of the combined effects of imprecise dietary measurements and limited variability of dietary intakes within each cohort.

Dietary fat and breast cancer

One of the most often studied associations in epidemiology is dietary fat and breast cancer risk. That migrants from low-risk countries increase their risk on immigrating to higher-risk countries suggests that some modifiable lifestyle or environmental factor is responsible for the development of breast cancer. Although early international correlational studies and experimental animals studies support dietary fat as a risk factor for breast cancer, more recent data from case-control studies and cohort studies have been equivocal, thus the analytical data do not support a strong positive association. The conflicting results from analytic studies may be due to methodologic issues associated with study design, dietary assessment tools, measurement error, improper statistical analyses, and a lack of heterogeneity in fat intake among the study population. Moreover, current dietary questionnaires may be inadequate in capturing true dietary intakes or capturing the risk with exposure during earlier periods of a woman's life. Although two large clinical trials investigating the fat/breast cancer relationships issue are underway, researchers are generally skeptical at their ability to detect an independent association between fat and breast cancer risk. Further epidemiologic studies using current methodology may not prove to be fruitful in generating definitive answers to shed light on this controversial issue. In addition, rather than concentrating on dietary fat, researchers should focus on diets that are not only low in saturated fat, but also high in fruit and vegetable consumption. Researchers should take advantage of advances in molecular and genetic technology for a different perspective in examining the issue. For example, markers of susceptibility to breast cancer that can detect women at higher risk for breast cancer may be helpful in clarifying the role of dietary fat. More comprehensive and multiple approaches to studying dietary factors and breast cancer are recommended.

Meta-analysis of studies on breast cancer risk and diet: the role of fruit and vegetable consumption and the intake of associated micronutrients

A meta-analysis was carried out, in order to summarise published data on the relationship between breast cancer, fruit and vegetable consumption and/or the intake of beta-carotene and vitamin C. Relative risks were extracted from 26 published studies from 1982 to 1997. Random and fixed effects models were used. Between studies, heterogeneity was found for vegetables, fruit, vitamin C but not for beta-carotene. Summary relative risk (RR) estimates based upon a random effects model, except for beta-carotene, for 'high consumption' compared with 'low consumption', derived from the studies satisfying the inclusion criteria were as follows: vegetable consumption: RR=0.75 (95% CI (confidence interval) 0.66-0.85) from 17 studies; fruit consumption: RR=0.94 (95% CI 0.79-1.11) from 12 studies; vitamin C: RR=0.80 (95% CI 0.68-0.95) from 9 studies; beta-carotene: RR=0.82 (95% CI 0.76-0.91) from 11 studies. This analysis confirms the association between intake of vegetables and, to a lesser extent, fruits and breast cancer risk from published sources. Increasing vegetable consumption might reduce the risk of breast cancer.

Breast cancer: aetiological factors and associations (a possible protective role of phytoestrogens)

BACKGROUND

In spite of many known and suspected factors associated with the risk of breast cancer there has until recently been no explanation for its continuing increase in women of Western societies over recent decades or why there has not been an equivalent increase in women of most Asian and other less Westernized societies. It has long been suspected that a significant factor has been an increasing change of diet in Western societies from one predominantly vegetarian to one with a high content of meat and dairy products as well as 'refined' foods. Although diet has long been suspected there has otherwise been no real explanation as to the mechanism of the change in incidence of breast cancer.

METHODS

A comprehensive literature review has been made of aetiological factors and associations concerning breast cancer to determine whether any consistent trend can explain the rising incidence in Western societies.

RESULTS

There are a number of likely contributory factors but there is now accumulating evidence that the single most important difference is that people having a vegetarian diet have a high intake of legumes and other plant foods containing a variety of lignans and isoflavonoids. These appear to have an important role as nature's sex hormone modulators. These agents appear to be biologically active in a number of ways not yet completely understood but they do have both a weak oestrogenic effect and an anti-oestrogenic competitive effect, thus reducing the potential carcinogenic action of prolonged oestrogen activity. A probable additional benefit of such diets could be the role of dietary fibre.

CONCLUSIONS

A major problem of Western diets may not be the presence of meat or dairy products in the diet but the absence of desirable ingredients of vegetarian diets, namely dietary fibre and certain plant lignans and isoflavonoids. A modification of diet to include a greater proportion of fibre and soy or other leguminous plant food should be studied. Alternatively addition of more fibre and lignans and especially isoflavonoids to traditional Western diets would seem worthy of serious investigation. Such influences appear to have their greatest impact early in life and therefore could be especially important for girls and young women in Western societies.