| Colorectal cancer (CRC) and breast cancer (BC) have a high incidence with mortality in most industrialized countries. Discrepancies in findings on the association between dietary fats and these two important cancers persist. This controversy was partly due to the fact that very little attention has been paid to specific fatty acids (FA), which are postulated to exert effects on both the promotion and inhibition of tumor formation and growth, because of their physiological functions. This study is undertaken to verify the hypothesis that differences observed in CRC and BC risk associated with dietary fats are attributed to specific FA consumed. This investigation also explores whether CRC and BC risk associated with individual polyunsaturated fatty acids (PUFA) differs with regard to intake of antioxidants, since persistent oxidative stress, involving enhanced peroxidation of PUFA in cell membranes by free radicals and reactive species is known to modulate the development of malignant diseases. (A) Colorectal cancer: After adjustment for age, marital status, history of CRC in first-degree relatives, body mass index 1 year prior to diagnosis, physical activity, and total energy intake; a significant inverse association was found among females between CRC and butyrate [OR = 0.57; 95% CI (0.34–0.96); P = 0.006], α-linoleic acid (ALA) [OR = 0.78; 95% CI (0.46–1.32); P = 0.016], and ω-3 FAs [OR = 0.84; 95% CI (0.50–1.41); P = 0.028], comparing the upper to the lower quartiles of intake. Similar trends were obtained among males without reaching statistical significance. An increased risk was associated with the ω6/ω3 ratio [OR = 1.47; 95% CI (0.86–2.50); P = 0.001] in women. Among males, arachidonic acid (AA) was directly associated with CRC [OR = 2.03; 95% CI (1.16–3.54); P = 0.001], and the risk increased up to about 5-fold [OR = 5.33; 95% CI (2.04–13.95); P = 0.0004 for trend]{09} among those with high vitamin C intake. (B) Breast cancer: After adjustment for age at first-full term pregnancy, number of full-term pregnancies, history of BC in first-degree relatives, history of benign breast disease, smoking, marital status, and total energy intake; no overall association was found between specific fatty acids and BC risk. Among postmenopausal women, an interaction effect on BC risk was detected between AA and vitamin E (P for interaction = 0.013). (Abstract shortened by UMI.)... |
