TUESDAY, March 25 (HealthDay News) -- European researchers report more grim news concerning women and hormone replacement therapy: Not only do healthy women run the risk of developing breast cancer while taking the therapy, breast cancer survivors who do the same face a higher risk of a recurrence or a new malignancy.
"This is the first study where patients with relatively recent breast cancer were randomized to take either hormone therapy or to do alternative therapies," said Dr. Jennifer Wu, an obstetrician/gynecologist with Lenox Hill Hospital in New York City. "Really, at this point, there's no guarantee of the safety of hormone replacement therapy in breast cancer survivors. Some forms of estrogen and progestin and different regimens of those two may be safer, but the risks are pretty clear-cut."
The study, conducted by researchers from King's College London and Scandinavia, is published in the March 25 online issue of the Journal of the National Cancer Institute.
Several studies have pointed to an increased risk of breast cancer in healthy women taking hormone replacement therapy (HRT) for menopausal symptoms, but the evidence on breast cancer survivors has been limited.
"Previously, there were basically case studies, observational studies, and it looks like our data was a little bit biased," Wu said. "People who had been chosen to go on HRT probably were people who were years out from their diagnosis, who didn't have [estrogen receptor]-positive nodes, who had been doing very well."
This new trial was originally designed to see if HRT was safe to counter menopausal symptoms in women who had already had breast cancer. Women were randomly chosen to receive either hormone therapy or alternative methods of managing menopausal symptoms.
The researchers halted the trial early when it appeared that women taking HRT had a higher risk of breast cancer recurrence.
The current data, which represents a median of about four years of follow-up in 442 women, showed a 17.6 percent risk of a recurrence or a new tumor in the HRT group, compared with a 7.7 percent risk among women in the control group. The estimated five-year risk for a recurrence was 22.2 percent for women in the HRT group and 9.5 percent in the control arm, translating into a 14.2 percent absolute increased risk for women taking hormones.
Women in the trial had both estrogen receptor-positive and estrogen receptor-negative cancers. Estrogen receptor-positive cancer is fueled by the hormone estrogen.
The study did not determine if taking HRT increases the risk of dying from breast cancer.
For women in general, the message remains the same: They should avoid taking hormone therapy unless needed for severe menopausal symptoms, and then at the lowest dose possible for the shortest amount of time.
"For breast cancer survivors, the stakes are higher," said Debbie Saslow, director of breast and gynecologic cancer at the American Cancer Society. "My guess is that women survivors who would even consider HRT would be those with the best prognosis and severe menopausal symptoms. It's not recommended, but for some women that quality of life is important. You need to keep it all in perspective."
Visit the U.S. National Cancer Institute for more on breast cancer.