In a move that continues to add to the evidence that hormone replacement therapy may be dangerous, Scandinavian researchers on Tuesday called off a study on HRT for women with a history of breast cancer because early results showed an "unacceptably high" risk of recurrence. Their findings, published Tuesday in The Lancet, add to the already solid evidence that using hormone replacement to control menopausal symptoms such as hot flashes and prevent brittle bones carries significant health risks. Eighteen months ago, U.S. government scientists abruptly ended the nation's biggest study of HRT using the combined hormones estrogen and progestin, saying long-term use significantly increases women's risk of breast cancer, strokes, and heart attacks. That study involved older women who were well past menopause. Last year, a U.K. study concluded that women receiving HRT had a 22% higher risk of death from breast cancer than women who were not and that those who used estrogen and progestin together had a markedly higher risk than those who used estrogen alone.
The Scandinavian researchers, led by Lars Holmberg from University Hospital in Uppsala, Sweden, had intended to follow their patients for five years. They said they called off the study on December 17 based on results from 345 women they had been following for an average of two years. Half the women were given HRT, and the other half the best nonhormonal treatment for menopausal symptoms. In the HRT group, 26 women had a recurrence or a new case of breast cancer. That compared with seven women among those who took the other treatment.
At the American Cancer Society, Harmon Eyre noted that doctors occasionally offer hormone replacement to breast cancer survivors with severe menopausal symptoms because a handful of small, preliminary studies showed no risk. "This study will no doubt change that," said Eyre. "It is large enough and clear enough to show that HRT appears to increase the chance of a new or recurring breast cancer."