HRT After Breast Cancer Does Not Increase Risk Of Cancer Recurrence Or Mortality

There has been lots of conflicting news about the relationship between hormone replacement therapy and breast cancer. The latest study to address this issue comes from the Journal of the National Cancer Institute (5/16/01). The study found that for women who have already had breast cancer, hormone replacement therapy did NOT increase their risk of breast cancer recurrence. In fact, the study found that HRT might even lower the chances of a breast cancer recurrence in those women and lower their risk of death from breast cancer if it does recur.  In addition, this study showed that HRT use after a diagnosis of breast cancer reduced the relative risk of death from all causes.

Investigators at the University of Washington in Seattle evaluated data from 2,755 women, aged 35 to 74, who had been diagnosed with invasive breast cancer between 1977 and 1994. Of these women, there were 174 who elected to use hormone replacement therapy after their diagnosis.  Each of those HRT users was matched to 4 randomly selected nonusers with similar age, disease stage, and year of diagnosis.  After following these women for approximately 4 years, rates of breast cancer recurrence and death from all causes was calculated. The results show that the rate of breast cancer recurrence was 17 per 1000 person-years in women who used HRT after their diagnosis of breast cancer, and nearly twice as high (30 per 1000 person-years) in women who did not use HRT after their diagnosis.  Breast cancer mortality rates were 5 per 1000 person-years in HRT users and three times higher (15 per 1000 person-years) in nonusers. Mortality rates from all causes were nearly twice as high in the women who did not use HRT (16 per 1000 person-years in HRT users versus 30 per 1000 person-years in nonusers).

What do these numbers mean in plain English? After following these women for nearly 4 years, investigators found that the rate of cancer recurrence in women who used HRT after having been diagnosed with invasive breast cancer was approximately HALF of what it was in nonusers after adjustment for confounding factors.

When they evaluated causes of death in these women, the researchers found that the risk of death from breast cancer was three times greater in the women who did NOT use HRT than in the women who did.  When death from ALL causes was evaluated, the women who did not take HRT had TWICE the risk of death compared to the women who took HRT. The results did not vary based upon the length of time that the women took HRT or whether they used the vaginal or pill form of HRT.

The results of this study argue against any causal influence of HRT on breast cancer recurrence and mortality.  It may also influence the recommendations that women are given about resuming HRT after breast cancer diagnosis.

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Created: 5/24/2001  -  Donnica Moore, M.D.