Diet and breast cancer

Serum enterolactone concentration is not associated with breast cancer risk in a nested case-control study

The lignan enterolactone produced by the intestinal microflora from dietary precursors has been hypothesized to protect against hormone-dependent cancers. We conducted a nested case-control study to examine the relationship between serum enterolactone concentration and risk of breast cancer. Enterolactone concentrations were measured by time-resolved fluoroimmunoassay in serum collected at 4 independent cross-sectional population surveys from 206 women with breast cancer diagnosed during follow-up (mean 8.0 years) and from 215 controls frequency-matched to cases by study cohort, 5-year age group and study area. Mean serum enterolactone concentration (nmol/l) did not significantly differ between case and control subjects [25.2 (SD 22.2) vs. 24.0 (SD 21.3), respectively]. Odds ratios for breast cancer risk estimated by conditional logistic regression for increasing concentration of enterolactone in quartiles were 1.00 (referent), 1.67 (95% CI 0.95-2.95), 1.71 (95% CI 0.96-3.06) and 1.30 (95% CI 0.73-2.31), and p for trend was 0.48. Our findings do not support the hypothesis that high serum enterolactone concentration is associated with reduced risk of breast cancer.

Dietary fat and cancer

Based on current epidemiologic knowledge, public health recommendations to decrease total fat intake for the prevention of cancer appear largely unwarranted. Recommendations to decrease red meat intake, particularly processed meat or beef intake, may, on the other hand, decrease the risk of colorectal cancer and prostate cancer; it may have a beneficial effect on breast cancer as well, although the evidence is much less compelling in this regard. There appears to be no particular benefit regarding cancer prevention that would accrue from reducing fat intake from vegetable sources, and in the case of breast cancer, there is some suggestive but preliminary evidence that olive oil or other sources of monounsaturated fatty acids may modestly decrease risk. Overall, recommendations focused on controlling weight by regular physical activity and avoidance of excessive energy intake from all sources; increasing plant food intake; consuming a variety of whole grains, vegetables, and fruits; and decreasing red meat intake are likely to be more effective in decreasing risk of breast, colorectal, and prostate cancer than decreasing total fat intake. This conclusion is consistent with current recommendations for cancer prevention as promulgated by the American Cancer Society.

Are vitamin and mineral deficiencies a major cancer risk?

Diet is estimated to contribute to about one-third of preventable cancers -- about the same amount as smoking. Inadequate intake of essential vitamins and minerals might explain the epidemiological findings that people who eat only small amounts of fruits and vegetables have an increased risk of developing cancer. Recent experimental evidence indicates that vitamin and mineral deficiencies can lead to DNA damage. Optimizing vitamin and mineral intake by encouraging dietary change, multivitamin and mineral supplements, and fortifying foods might therefore prevent cancer and other chronic diseases.

Interaction between alcohol dehydrogenase II gene, alcohol consumption, and risk for breast cancer

MaeIII Restriction Fragment Length Polymorphism in exon 3 of the alcohol dehydrogenase II was assessed in serum from 467 randomly selected German women and 278 women with invasive breast cancer to evaluate the interaction between a polymorphism of the alcohol dehydrogenase II gene, alcohol consumption and risk for breast cancer. In both groups, usual consumption of different alcoholic beverages was asked for using semiquantitative food frequency questionnaires. We used multivariable logistic regression to separately estimate the association between alcohol consumption and alcohol dehydrogenase II polymorphism in the population sample and women with breast cancer. The alcohol dehydrogenase II polymorphism was detected in 14 women from the population sample (3.0%) and in 27 women with invasive breast cancer (9.7%). Frequency of alcohol consumption was independent of the genotype in the population sample. In women with breast cancer, there was a significant inverse association between the alcohol dehydrogenase II polymorphism and frequency of alcohol consumption (adjusted case-only odds ratio over increasing frequency of alcohol consumption=0.5; P for interaction=0.02). We observed a gene-environment interaction between the alcohol dehydrogenase II polymorphism, alcohol consumption, and risk for breast cancer. Breast cancer risk associated with alcohol consumption may vary according to the alcohol dehydrogenase II polymorphism, probably due to differences in alcohol metabolism.

Diet and environmental carcinogenesis in breast/gynaecological cancers

This paper reports on recent advances on the relation between diet, other environmental factors and breast and gynaecological cancers. Despite considerable research the issue remains still unsettled. The protective effect of a diet rich in vegetables and fruit, and thus selected (antioxidant) micronutrients, is not consistently reported in various studies. The possible relationship between fats and breast and female genital tract neoplasms also remains unconfirmed, while the potential benefits of physical activity remains unquantified. Alcohol appears to be related to the risk of breast cancer and overweight is associated with post-menopausal breast cancer and is strongly related to the risk of endometrial cancer.

An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates

BACKGROUND

The role of diet in the etiology of breast carcinoma has been debated for decades. The ecologic approach generally finds that dietary fat is highly associated with breast carcinoma mortality, with fish intake and solar ultraviolet-B (UV-B) radiation, a source of vitamin D, inversely associated. Case-control and cohort studies generally find a variety of chemical, nonfat dietary, environmental, genetic, lifestyle, and reproductive factors to be important.

METHODS

An ecologic study was conducted using breast carcinoma mortality rates (1989-1996), dietary supply data, and latitude (an index of solar UV-B radiation) from 35 countries.

RESULTS

The fraction of energy derived from animal products (risk) combined with that from vegetable products (risk reduction), followed by solar UV-B radiation and, to a lesser extent, energy derived from alcohol (risk) and fish intake (risk reduction), were found to explain 80% of the variance of breast carcinoma mortality rates. Dietary fat contributed insignificantly in regressions involving the other factors.

CONCLUSIONS

It is hypothesized that animal products are associated with risk for breast carcinoma because they are associated with greater amounts of insulin-like growth factor-1 and lifetime doses of estrogen. Vegetable products contain several risk reduction components including antioxidants and phytoestrogens. The association with latitude is very likely because of solar UV-B radiation and vitamin D. Alcohol modulates estrogen's effects on breasts. Fish intake is associated with risk reduction through vitamin D and n-3 oils. These results are consistent with those of many case-control and cohort studies but should be assessed in well designed cohort studies.