My friend (and occasional guest blogger here at the Voice of Reason) Dr. Avrum Bluming just co-authored an eye-opening exposé of breast cancer risk factors and how they’re overblown for media purposes. This article was published in the Los Angeles Times today. Here is an excerpt:
We now have a fat file folder of all the studies we could find that have reported an association between some purported risk factor and breast cancer. Of these, the ones that got the most attention were three Women’s Health Initiative reports. In 2002, investigators found an increased relative risk of 26% from using combined estrogen and progesterone; in 2003, it was 24%; and in 2004, the relative risk from using estrogen alone was minus 23% (suggesting it was protective against breast cancer).
To put those findings in perspective, consider these published studies showing the increased relative risk of breast cancer from:
* eating fish: 14%
* eating a quarter of a grapefruit a day: 30%
* gaining more than 33 pounds in pregnancy: 61%
* being a Finnish flight attendant: 87%
* being a Dutch survivor of childhood famine: 201%
* using antibiotics: 207%
* having a diagnostic chest X-ray: 219%
* being an Icelandic flight attendant: 410%
* using an electric blanket: 630% (but only if you are a black woman who used it for more than 10 years but less than six months in a given year).
Why was there no call for Icelandic flight attendants to quit (or transfer to Lufthansa), for black women to use electric blankets for more than six months a year but only for nine years, for labeling antibiotics as carcinogens? Because these findings, which were improbable to begin with, were never replicated. In contrast, the increased relative risk of lung cancer from smoking is consistently between 2,000% and 3,000%. That’s a finding that means something.
Unfortunately, good news doesn’t travel as fast as fear does. In 2006, the Women’s Health Initiative investigators reanalyzed their data and found that the risk of breast cancer among women who had been randomly assigned to take hormone replacement therapy was no longer significant. Women assigned to take a placebo but who had used hormone replacement therapy in the past actually had a lower rate of breast cancer than women who had never taken hormones.
This reassuring but non-scary news did not make headlines…