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March 1, 2009
BODY WEIGHT AND BREAST CANCER
 A study was published in 2005 on 98,000 postmenopausal women from six European countries looking at weight gain in adulthood (after age 20) as a risk factor for breast cancer. In postmenopausal women who were not currently using hormone replacement therapy weight gain was associated with an increased risk of breast cancer. Women who gained between 20-40 lb after age twenty increased their risk of breast cancer by 50%. (Please note that women who used HRT had an increased risk of breast cancer; but the additional weight gain did not add to this risk. See my February message for details on HRT and breast cancer risk.)
The researchers who conducted this very large study concluded "large adult weight gain was a significant predictor of breast cancer in postmenopausal women."
Why might that be?
The fat in your body does more than just store energy. It seems that body fat is a kind of body organ of its own: it manufactures several items that have an impact on the rest of the body. One of the things that body fat makes is estrogen. The more body fat you have the more estrogen you are making. So even if your ovaries have shut down (menopause) and your overall estrogen levels are relatively low, excess body fat continues to pour out quantities of estrogen – and estrogen is well-known promoter of breast cancer.
Another European study, this time of 174,000 women from nine countries, also looked at body weight as a risk factor for breast cancer. They found the same thing: in postmenopausal women general obesity was a significant predictor of breast cancer.
For women who have already had breast cancer body weight is a risk factor for breast cancer recurrence and increased mortality. The scientists who published these results felt that sufficient evidence warranted life-style interventions for breast cancer patients to help them maintain normal body weight.
In order to reduce your risk of breast cancer, or reduce your mortality if you already have had the disease I would recommend the following:
- Maintain your ideal body weight. If you need help with dieting, I can recommend Weight Watchers. I have had many patients use the Weight Watchers diet and meal plans with great success – but you have to stick with it, permanently. Go ahead and try other weight loss programs if you like, but understand that your diet and nutrition need to change permanently.
- Exercise regularly. You don’t have to work hard, but you must exercise regularly. Just walking 4 hours per week is perfectly fine and will reduce your risk of breast cancer, breast cancer recurrence and breast cancer mortality. Regular exercise will also help your burn more calories and help you maintain your ideal body weight.
In summary: if you need to lose weight then do so. Maintain ideal body weight and exercise regularly. Just do it.
For your information, the articles referenced above are:
- Lahmann, British Journal of Cancer, Vol 93, No. 5, 2005, 582-89.
- Lahmann, International Journal of Cancer, Vol 111, No 5, 2004, 762-771.
- Chlebowski, Journal of Clinical Oncology, Vol 23, No 7, 2005, 1345-1347
Regards,
Kathleen T. Ruddy, MD
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