Feb. 2, 2004 -- Even short-term use of hormone therapy poses an "unacceptably high" risk of breast cancer recurrence. A Swedish study has been halted because of this finding, according to a report in The Lancet.
The study was investigating whether menopausal hormone therapy using estrogen and progestin is safe in women who are breast cancer survivors -- whether it would put these women at risk for a recurrence of breast cancer.
After all, the number of premenopausal women who survive breast cancer is growing. And modern cancer treatments often induce early menopause.
Some evidence has suggested that menopausal hormone therapy only slightly affects a woman's risk of breast cancer recurrence. However, since many breast cancers are fed by estrogen, the risks to survivors "call for caution," he writes.
Only 345 women had been enrolled in the study when it was halted in December 2003, writes Holmberg. All were survivors of stage I or II breast cancer.
Half of the women were getting menopausal hormone therapy and half were not.
After just two years of follow-up, 26 women receiving hormone therapy and seven in the non-hormone therapy group had breast cancer recurrences. The risk of developing a recurrence of breast cancer in women receiving hormone therapy was three times higher than those not receiving hormone therapy.
"We decided that these findings indicated an unacceptable risk for women exposed to [menopausal hormone therapy]," Holmberg reports.
"The effect of menopausal hormone-replacement therapy on breast cancer risk has been controversial for decades," writes Rowan T. Chlebowski, with Harbor-UCLA Research and Education Institute in Torrance, Calif. His commentary also appears in The Lancet.
This new evidence shows that even short-term use of hormone therapy "poses an unacceptably high risk" of breast cancer recurrence, he writes. Researchers must develop safe and effective alternatives for treating hot flashes and other difficult menopausal symptoms, he says.