Positive Health Online

Abstract

BRAGA and colleagues, Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy conducted a case-control study to investigate the relationship between foods and nutrients and breast cancer risk by age and menopausal status strata.

Background

Methodology

Cases were 2,569 women with histologically confirmed breast cancer admitted to major teaching and general hospitals from 6 Italian areas between June 1991 and April 1994 controls were 2,588 women with no history of cancer admitted to hospitals in the same catchment area for acute, non-cancerous, non-gynaecological conditions unrelated to hormonal or digestive tract diseases or to long-term diet modifications. The authors investigated dietary habits using a validated food frequency questionnaire, including 78 foods or food groups.

Results

Among food groups, bread was directly and significantly related to breast cancer risk in older women and in postmenopause. Protection conferred by fish consumption was stronger in postmenopause and protection exerted by raw vegetables was stronger in premenopause. Regarding nutrients, unsaturated fatty acids were inversely related to breast cancer risk, this association being stronger in postmenopausal and elderly women . A similar pattern was detected for total fats. Regarding starch, available carbohydrates and total proteins, there was no heterogeneity across strata of age and menopausal status. Regarding micronutrients, protection decreased with increasing age for beta-carotene and calcium and there was no heterogeneity for vitamin E.

Conclusion

This largest investigation to date regarding age-specific analysis of diet and breast cancer did not show any consistent pattern of breast cancer risk regarding specific dietary factors across strata of age and menopausal status.

References

Braga C et al. Intake of selected foods and nutrients and breast cancer risk: an age- and menopause-specific analysis. Nutr Cancer 28 (3): 258-63 1997.

Comment

Does this study possibly suggest that dietary questionnaires are not specifically useful for these types of epidemiological studies? I openly declare my caution regarding epidemiological studies for populations of consumers who are highly divergent in their eating habits of the incredibly wide range of foods available. What is also lacking in almost all studies of this type is an analysis of the quality of the foods eaten, whether they contained pesticides, antibiotics, growth-promoting hormones or poisons, whether they were fresh enough to contain the micronutrients they are supposed to contain. Since it is becoming increasingly clear that the source of the cancer epidemic is largely environmental, ie in the food, water and air, research, difficult as it may be to design, must start to address these questions.