The women's health initiative: will it resolve the issues?

Dietary fat reduction to reduce prostate cancer risk: controlled enthusiasm, learning a lesson from breast or other cancers, and the big picture

Breast and prostate cancer share similar intrinsic and extrinsic risk factors. Based on laboratory, ecologic/international comparison, and case-control studies, the impact of dietary fat or other fat subtypes has been suggested as a potential route to reduce risk. Recent large-scale prospective studies have failed to find an association between fat and breast cancer risk. These studies may provide some insight for researchers examining the relation between fat and prostate cancer. Prospective studies to date have also failed to find a consistent association between prostate cancer and fat intake. Some fat subtypes (eg, saturated fat) or other lifestyle changes (eg, obesity, physical activity) may affect risk and progression of these cancers when examining the sum total of the research, but more precise and specific investigations in humans are needed to address these issues. Other concerns, such as the impact of excess energy or overall caloric consumption on carcinogenesis, still need to be addressed, as well as other methodologic limitations of past investigations. Large gaps exist in environmental (eg, diet, lifestyle) and heritable causes of these diseases. Regardless, until more extensive research is completed, lifestyle changes should be recommended based on reducing morbidity and mortality from cardiovascular disease-the number 1 cause of death in the United States. Additionally, cardiovascular disease remains the number 1 or 2 cause of death in patients diagnosed with breast or prostate cancer. Practical and simple dietary changes should be encouraged by health professionals because they could improve the overall longevity and quality of patients' lives. Numerous ongoing prospective studies of diet and cancer should provide researchers and the public with much-needed answers in this area.

Dietary modulation of omega-3/omega-6 polyunsaturated fatty acid ratios in patients with breast cancer

BACKGROUND

Polyunsaturated fatty acids of the omega-6 (omega-6) class, as found in corn and safflower oils, can act as precursors for intermediates involved in the growth of mammary tumors when fed to animals, whereas polyunsaturated fatty acids of the omega-3 (omega-3) class, as found in fish oil, can inhibit these effects. The effects of dietary intervention on the ratios of these fatty acids in breast and other adipose tissues have not previously been prospectively studied.

PURPOSE

The present investigation was conducted to study the impact on the ratio of omega-3 and omega-6 polyunsaturated fatty acid in plasma and in adipose tissue of the breast and buttocks when women with breast cancer consume a low-fat diet and fish oil supplements.

METHODS

Twenty-five women with high-risk localized breast cancer were enrolled in a dietary intervention program that required them to eat a low-fat diet and take a daily fish oil supplement throughout a 3-month period. Breast and gluteal fat biopsy specimens were obtained from each woman before and after dietary intervention. The fatty acid compositions of specimens of plasma, breast fat, and gluteal fat were determined by gas-liquid chromatography. Statistical analysis involved use of a two-sided paired t test.

RESULTS

After dietary intervention, a reduction in the level of total omega-6 polyunsaturated fatty acids in the plasma was observed (P<.0003); moreover, total omega-3 polyunsaturated fatty acids increased approximately three-fold (P<.0001) and the omega-3/omega-6 polyunsaturated fatty acids ratio increased approximately fourfold (i.e., mean values increased from 0.09 to 0.41; P = .0001). An increase in total omega-3 polyunsaturated fatty acids in breast adipose tissue was observed following dietary intervention (P = .04); the omega-3/omega-6 polyunsaturated fatty acid ratio increased from a mean value of 0.05 to 0.07 (P = .0001). An increase in total omega-3 polyunsaturated fatty acids was observed in gluteal adipose tissue following the intervention (P = .05); however, the ratio of omega-3 to omega-6 polyunsaturated fatty acids (mean ratio values of 0.036-0.045; P = .06) was unchanged.

CONCLUSION

Short-term dietary intervention can lead to statistically significant increases in omega-3/omega-6 polyunsaturated fatty acid ratios in plasma and breast adipose tissue. Breast adipose tissue changed more rapidly than gluteal adipose tissue in response to the dietary modification tested in this study. Therefore, gluteal adipose tissue may not be a useful surrogate to study the effect of diet on breast adipose tissue.