Menopause news

Hormone replacement therapy (HRT) cuts a woman's risk of developing colon cancer, new research confirms.

13 April 2010

Millions of women stopped taking HRT when the Women's Health Initiative study suggested in 2002 that the hormones raised the risk of stroke, heart disease and breast cancer.

But the Women's Health Initiative had also found that HRT protected against colon cancer. Some studies have also suggested that oral contraceptives might reduce the risk of the disease, while the fact that women are at lower risk of colon cancer than men also hints at a hormonal role in disease risk.

To investigate ties between HRT and colon cancer further, Dr. Millie D. Long of the University of North Carolina at Chapel Hill and her colleagues matched 443 women diagnosed between 2001 and 2006 with distal large bowel cancer (meaning tumors at the far end of the colon and the rectum) to 405 healthy control women. The average age of the study participants was around 63.

Long's team found that women who had ever used HRT were at half the risk of this type of colon cancer compared to women who'd never used hormone replacement, and the longer a woman was on HRT, the lower the risk.

For example, women who used hormones for less than four years cut their colon cancer risk by about one-quarter; four to eight years of HRT cut risk by a third; nine to 14 years of use halved risk; and 15 years or more of HRT reduced risk by two-thirds. The effects were the same for African-American women and white women.

However, there was no relationship between oral contraceptive use and colon cancer risk, the study team reports in the American Journal of Gastroenterology.

The major drop off in distal large bowel cancer in recent years could have been related to widespread use of HRT, the researchers say.

More research is needed to determine if HRT's protective effects persist after women stop taking hormones, the researchers add, or whether there might be a "rebound" effect with more pre-cancerous polyps developing after a woman stops taking HRT.

SOURCE: The American Journal of Gastroenterology, online March 30, 2010.

Comment: Evidence for a protective effect of HRT on bowel cancer seems to be increasing but we still don't know the scientific reason for this, and whether or not different types and routes of HRT have differing effects. Although it may seem tempting to suggest that women at particular risk of developing bowel cancer, eg if they have a family history of the disease, or if they have a personal history of inflammatory bowel disease, should take HRT to lower their risk, we are not yet in a position to recommend that HRT should be taken purely for this reason. However, women taking HRT for control of menopausal symptoms can be reassured that they may well benefit from this additional effect.

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