Weighing the Risks of Hormone Therapy

There was positive news in the study as well. The relative risks for colon cancer and hip fracture were both .67, suggesting that women on HRT will suffer only 67 percent the number of colon cancers (12 instead of 18 out of 10,000) and hip fractures (10 instead of 15) as women not on it. In addition, the women on HRT suffered far fewer other fractures, debilitating breaks of the shoulders, arms, and legs often associated with osteoporosis. The study did not attempt to measure the considerable value of HRT in treating hot flashes, sleep disturbances, depressions, skin and hair problems, and perceived lapses in mental acuity.

Still Not Clear-Cut

The decision whether to begin or continue HRT treatment is a complicated and personal one, but, the tenor of the coverage notwithstanding, there are reasons to do so.

The primary one, of course, is that the benefits in the previous paragraph (as well as others) sometimes manifestly outweigh the risks. Related to this is the fact that the relative risks are not that great. Another consideration is that the study's conclusions may merely be the result of a hidden statistical bias (as there was with the opposite conclusions reached by earlier studies). Terminating the study prematurely as the WHI researchers did, for example, might have introduced some bias by stopping a naturally fluctuating sequence of numbers on an upswing.

Although some of the study's conclusion were statistically significant, they were just barely so. As mentioned, relative risks of less than two are often not taken very seriously. (They can even arise from publication bias — the throwing out of studies that find no or slightly beneficial effects and the hyping of spurious slightly harmful effects.)

By contrast, the relative risk of lung cancer among smokers is flat-out undeniable — somewhere around 15 (with different studies producing values ranging between 10 and 25); that is, smokers are roughly 15 times as likely to develop lung cancer as are non-smokers.

Compare this with the HRT relative risks of approximately 1.3.

Hormone replacement therapy is not the panacea it was once touted to be. Neither is it the significant carcinogen that some accounts have described it to be. Like a lot of treatments, like a lot of life, it appears to be a trade-off.

Professor of mathematics at Temple University and adjunct professor of journalism at Columbia University, John Allen Paulos is the author of several best-selling books, including Innumeracy and A Mathematician Reads the Newspaper. His Who’s Counting? column on ABCNEWS.com appears the first weekend of every month.

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