Breast Cancer Recurrence
The Jury's in
The jury is in: hormone replacement therapy (HRT) increases the risk that survivors of breast cancer will have a recurrence of the disease. HRT is a popular therapy for women who are perimenopausal, menopausal and postmenopausal, and is often prescribed for use for an indefinite period of time. While it is already known that HRT gives a slight increase for breast cancer in healthy women, this is the first complete study to concentrate on the ramifications of this therapy on breast cancer survivors.
Some previous studies and trials had suggested that HRT either had no effect on disease recurrence, or may even reduce recurrence. This was later contradicted by the two year follow-up data brought to the medical community by the HABITS (Hormonal Replacement After Breast Cancer—Is It Safe?) trial. In this study, there was an indication that those survivors taking HRT had more of an increase in the risk of a disease recurrence than in those who refrained from taking HRT.
Now, London's King's College physician Lars Holmberg, M.D., Ph.D., and his team of Scandinavian colleagues have reported on their examination of the breast cancer rates for the women in the HABITS trial during a four year follow-up.
An analysis of the four year data had 39 of the 221 women in the HRT group, or 17.6%, as having developed a recurrence of breast cancer or a new breast cancer malignancy. This compares to 17 of the 221 women not on HRT, or 7.7 percent. It is estimated that the 5 year all around rate for a recurrence of breast cancer is 22.2% for the HRT group, and 9.5% in the control group. That puts the total risk at 14.2%.
The authors write that, "The results of the HABITS trial indicate a substantial risk for a new breast cancer event among breast cancer survivors using [HRT]. The risk elevation is in line with the evidence from observational studies and randomized trials that [HRT] increases the risk of breast cancer in healthy women."
Kathy I. Pritchard, M.D., of the Toronto Sunnybrook Odette Cancer Center, authored an editorial that appeared alongside the results of the trial in the Journal of the National Cancer Institute. This editorial discusses the HABITS trial findings as well as those of the Women's Health Initiative trial, which showed that the risk for breast cancer has increased among healthy women. Pritchard feels that these types of studies can be misleading, in so far as they have built in biases, for instance, relating to the type of women who are chosen as participants in such studies.
The Toronto doctor cited a random study from Stockholm which found there was no increased risk for a recurrence of breast cancer in survivors taking HRT and suggests that there may be important differences between the Stockholm trial and the HABITS study; for instance, HRT may be given according to a different timetable or strength, and the type of hormone used may differ. Any of these factors may have affected the outcome of these two studies which had such varied results.
The ultimate upshot of the data, however, is clear. "Although randomized data concerning use of HRT for symptomatic intervention in breast cancer survivors are still sparse, it seems that the harmful side effects of HRT have finally been clearly demonstrated," says Pritchard.