Nothing new in case-control study of long-term HRT, breast cancer

There’s nothing new under the sun.

That’s how doctors view the conclusions of a widely publicized case-control study that examined the long-term effects of hormone replacement therapy (HRT) in relation to breast cancer among more than 700 women who were post-menopausal. The article concluded that the incidence of breast cancer was increased by 60 percent-85 percent in recent long-term users of HRT whether they used estrogen alone or estrogen plus progestin.

It would be premature to say that it is conclusive when organizations such as the National Institutes of Health, the American College of Obstetricians and Gyneco-logists, and the National Cancer Institute have made statements saying that there is no conclusive evidence linking estrogen replacement therapy and HRT to breast cancer risk, according to a program leader of the gynecology oncology program at the H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida.

They don’t know the answer. They think they need to treat the patients the way they’ve always been treating them. Weigh all their risk factors, benefits, and quality of life. The study followed 705 women enrolled in the Group Health Cooperative of Puget Sound (Washington) aged 50-74 years who had primary invasive breast cancer diagnosed between 1990 and 1995. A total of 692 age-matched female controls were also included in the study.

Led by an epidemiologist at the Fred Hutchinson Cancer Research Center. Seattle, the investigators found that the relative risk of all types of breast cancer increased 60 percent-85 percent in women who took HRT for 57 months or more during a five-year period that ended in the year before diagnosis of their breast cancers.

However, one doctor, who is not affiliated with the study, took issue with the investigators’ decision to describe their findings in terms of increased relative risk rather than change in absolute risk. In terms of absolute risk, the associated risk that they described translates into an increase of 3.8 to 4.4 cases per 100 women.

So although it sounds like an enormous risk, when you break it down, it means an additional one to two breast cancers per 100 women. He also questioned the study’s reliance on pharmacy records for their data, noting that there is no way for investigators to determine the actual medications that were consumed by study participants.

They may have been taking soy products and over-the-counter medications, and other confounders. In another study findings, the investigators observed a threefold increase in the risk of lobular cancer and a 50 percent increase in nonlobular tumors in recent HRT users who took HRT for at least 57 months.

He predicted that clinicians will learn a great deal about the effects of HRT on breast cancer risk once results from the Women’s Health Initiative are available. The results from that randomized controlled trial are expected to be known in the next two to three years.