Canadian researchers reported a significant correlation between breast cancer risk and physical inactivity in post-menopausal women. The study, which was conducted in Alberta from 1995-97, included 1233 women with breast cancer and 1237 controls. All study participants underwent comprehensive interviews to determine their lifetime physical activity level, diet, smoking status, alcohol consumption, reproductive history, and body measurements. The researchers found no correlation between lifetime physical activity level and breast cancer risk in premenopausal women. Among postmenopausal women, however, a clear risk reduction with increased household and occupational physical activity was observed, but not with increased recreational physical activity. Women who had been most active during their lifetime (household and occupational) had an almost 40 per cent lower risk of breast cancer than did less active women. Active women who did not consume alcohol had a 61 per cent lower risk and active women who had not had any children (nulliparous) had a 78 per cent risk reduction. The researchers conclude that a high level of physical activity over a lifetime reduces the risk of breast cancer in postmenopausal women.

Friedenreich, C.M., et al. Case-control study of lifetime physical activity and breast cancer risk. American Journal of Epidemiology, Vol. 154, August 15, 2001, pp. 336-47

Exercise helps prevent breast cancer

Researchers at the University of Tromso report that women who exercise regularly reduce their risk of developing breast cancer substantially. Their study involved over 25,000 women aged 20 to 54 years at the entry to the study. During the 14-year follow-up period 351 of the women developed invasive breast cancer. The researchers found that younger, premenopausal women (less than 45 years of age) who exercised regularly had a 62 per cent reduction in risk as compared to sedentary women. The risk reduction was even higher for lean women (body mass index <22.8) who exercised more than four hours per week; these women had a 72 per cent reduction in risk. The reduction in breast cancer risk among postmenopausal women who exercised was less than than for younger women, but still highly significant. Both regular exercise and extensive physical activity during work were found to have a protective effect. The researchers speculate that regular physical activity lowers a woman's cumulative exposure to estrogen and progesterone, thereby inhibiting the development of breast cancer. Physical activity may also exhibit its protective effect by reducing obesity. Interestingly enough, the researchers also discovered that taller women were at increased risk while having a greater number of children reduced the risk. They found no correlation between total fat intake and breast cancer risk.

Thune, Inger, et al. Physical activity and the risk of breast cancer. New England Journal of Medicine, Vol. 336, May 1, 1997, pp. 1269-75

Glucarate and breast cancer prevention

Researchers at the Simone Protective Cancer Institute point out that perhaps 90 per cent of all cancers are caused by dietary or nutritional factors. It is also clear that inadequate removal or detoxification of carcinogenic substances in the body plays a significant role in cancer initiation and progression. Sold widely as supplements that may prevent estrogen-driven cancers, calcium D-glucarate is a precursor to a beta-glucuronidase inhibitor used clinically for phase 2 detoxification in the liver. Phase 2 detoxification accomplished via this inhibitor prevents conversion of tumor promoters into harmful active compounds. It also works by decreasing the absorption of estrogen hormones from the gut. Animal studies show reduction of beta-glucuronidase activity and a reduction in mammary cancer with an increase of calcium D-glucarate in the diet. Human clinical studies are being proposed to derive supportive evidence for the usage, but as this supplement is considered safe for human beings, many people continue to use calcium in this formulation.

Dosage

Calcium D-glucarate is found naturally in grapefruit, apples, oranges, broccoli, and Brussels sprouts. If a supplement is used, 200 to 400 mg is given for prevention, and 400 to 1200 mg is recommended for patients who have breast cancer.

Precautions

Although calcium D-glucarate is a very safe supplement with no major adverse effects, further research is needed to support its use.