Risks Small; Benefits Depend on Individual
The shocking thing about WHI wasn't its finding that women on HRT have an increased risk of breast cancer. The surprise was that HRT -- which earlier studies suggested would decrease risk of heart disease and stroke -- actually increased these risks. Moreover, there was a less-than-expected improvement in osteoporosis. It wasn't the size of these risks that stopped the trial, but the fact that the risks outweighed the benefit.
WHI was a clinical trial -- that is, women who entered the trial agreed to take the pills they were given, knowing that they had a 50-50 chance of getting HRT or placebo do-nothing pills. Earlier studies were observational -- they followed women already on HRT and looked at what happened.
"I think there is a lot of evidence that the observational studies of HRT are generally getting the right answers," Grodstein says. "Generally the risks seen for stroke, breast cancer, colon cancer, and pulmonary embolism are identical to those seen in clinical trials. Why the findings on heart disease were so different -- there are not a whole lot of answers right now. It may be that the women in the clinical trials were older. In terms of heart disease, there is some suspicion that if the disease process has gone a certain distance, it is hard to help it. Early intervention could work, but starting later in the disease process may make that same product have harm instead of benefits."
Caren Solomon, MD, MPH, deputy editor of TheNew England Journal of Medicine and a physician at Brigham and Women's Hospital, is co-author of the other NEJM paper.
"I think Dr. Grodstein's goal was to make sense of why randomized clinical trials looked so different from observational data," Solomon tells WebMD. "What we tried to do is say OK, given everything that is out there, what do we do? When should women use HRT, and if they should not use it, how should they stop it? We wanted to offer clinicians some very practical information."
Here's Solomon's advice to women: