The doses of estrogen and progestogen used in menopausal hormone therapy may be related to the risk of breast cancer recurrence, according to a new study in the April 6 issue of the Journal of the National Cancer Institute.
In 1997, two randomized trials, the Hormonal Replacement Therapy - Is It Safe? (HABITS) trial and the Stockholm trial, began in Sweden to test the effects of menopausal hormone therapy in women after they had been diagnosed with early-stage breast cancer. The HABITS trial, which ultimately included 434 breast cancer patients, was halted early in December 2003 because, at a median follow-up of only 2.1 years, the risk of breast cancer recurrence among women receiving hormone therapy was 3.3 times higher than the risk among women receiving no treatment.
Eva von Schoultz, M.D., Ph.D., and Lars E. Rutqvist, M.D., Ph.D., of the Karolinska Institutet, in Stockholm, Sweden, and the Stockholm Breast Cancer Study Group now report the results of the Stockholm trial, in which 378 breast cancer patients were randomly assigned to receive either menopausal hormone therapy for 5 years or no treatment. The trial was similar to the HABITS trial but used a hormone therapy regimen that differed in composition and timing.
In the Stockholm trial, after a median of 4.1 years of follow-up, there was no association between hormone therapy use and the risk of breast cancer recurrence. The authors suggest that differences in the composition and timing of the hormone therapy used in the Stockholm trial could explain why the trial’s results differed from those of the HABITS trial.