The scientific evidence on the preventive effects of omega-3 fatty acids in relation to cancer is mixed. Some studies show significant reductions in various cancer risks through supplementation with omega-3s and/or high dietary intake, while others show no association. In a study published in the December 2001 issue of "Japanese Journal of Cancer Research," researchers found an increased risk in lung cancer among women in relation to omega-3 consumption. On the other hand, the University of Maryland Medical Center reports evidence of omega-3 benefits compelling enough to recommend supplementation to help ward off lung cancer.
Omega-3s and Tumor Incidence
The Agency for Healthcare Research and Quality released a report in February 2005 in which it analyzed available data on the relationship between omega-3 fatty acids and cancer tumor incidence. The agency found four studies of statistical significance. Two lung cancer studies found a significant association between omega-3 consumption and risk; however, one for was increased risk while the other was for decreased risk. A statistically significant decrease in the risk of breast, prostate and skin cancers as a result of omega-3 consumption was reported. However, the agency concluded that omega-3s do not appear to decrease overall cancer risk.
Omega-3s and Prostate Cancer
Prostate cancer is the third most common cancer in men, with 543,000 new cases diagnosed each year. Researchers reporting in the March 2006 issue of "British Journal of Cancer" stated that diets rich in omega-3 fatty acids may help to reduce risk and inhibit disease progression. The team found that omega-6 fatty acids accelerated the spread of prostate cancer cells. However, when fish-derived omega-3 fats called EPA and DHA were present, the spread of cancer cells came to a halt. The researchers found that half as much omega-3 as omega-6 stopped cancer cells from spreading.
Omega-3s and Breast Cancer
Researchers reporting in the November 2003 issue of "British Journal of Cancer" examined data from the Singapore Chinese Health Study to investigate whether there was any relationship between dietary fats and breast cancer risk. Analysis of the 35,298 participating women demonstrated that high levels of dietary omega-3s were significantly associated with reduced risk. Specifically, analysis showed that postmenopausal women who consumed between 1.5 and 3 oz. of omega-3-rich marine foods every day cut their risk of developing breast cancer by 26 percent.
Omega-3s and Breast Fibrocysts
Breast fibrocysts are common in women, and about six in 10 will experience them. The most common type does not increase cancer risk; but the less common type, known as proliferative fibrocystic condition, is associated with a significantly greater risk of breast cancer. Researchers reporting in the December 2007 issue of "Cancer Epidemiological Biomarkers and Prevention" found that women with the highest blood levels of the omega-3 fat named EPA had less than half the risk of developing fibrocystic breasts and were about half as likely to have breast cancer.
References
- "Japanese Journal of Cancer Research"; Dietary Habits and Risk of Lung Cancer Death in a Large-Scale Cohort Study in Japan by Sex and Smoking Habit; K. Ozaska et al.; December 2001
- University of Maryland Medical Center: Lung Cancer
- "AHRQ Evidence Reports"; Effects of Omega-3 Fatty Acids on Cancer; C. MacLean et al.; February 2005
- "British Journal of Cancer"; Promotion of Prostatic Metastatic Migration Towards Human Bone Marrow Stoma by Omega-6 and Its Inhibition by Omega-3; M. Brown et al.; March 2006
- "British Journal of Cancer"; Opposing Effects of Dietary n-3 and n-6 Fatty Acids on Mammary Carcinogenesis: the Singapore Chinese Health Study; M. Gago-Dominguez et al.; November 2003
- "Cancer Epidemiological Biomarkers and Prevention"; Plasma Isoflavones and Fibrocystic Breast Conditions and Breast Cancer Among Women; J.W. Lampe et al.; December 2007
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