The combined hormone therapy also may make it more difficult to detect breast cancer, according to the study in the Archives of Internal Medicine, a publication of the Journal of the American Medical Association.

The report represents the latest findings from the Women's Health Initiative.

Researchers studied 16,608 post-menopausal women from 1993 through 1998: About half received a hormone therapy of estrogen plus progestin, while the other half received a placebo.

Each woman received a mammogram and breast examination yearly; biopsies were based on physicians' judgment.

Among women with a uterus who took the estrogen plus progestin, 199 developed breast cancer; 150 women in the placebo group developed breast cancer.

Mammograms with abnormal results were more common among women taking hormones (35 percent) than among women taking a placebo (23 percent); women taking hormones had a 4 percent greater risk of having a mammogram with abnormalities after one year and an 11 percent greater risk after five years.

An abnormal mammogram doesn't necessarily mean a woman has cancer.

"Abnormal means there is a question mark," said Yvonne Michael, a Kaiser clinical investigator. "It means they couldn't tell if there was cancer or not, and needed additional mammograms."

And that takes its own toll, even if a woman turns out to be cancer-free.

"There is a good potential for psychological harm, and a cost in both time and resources, that go into finding out that someone doesn't have a diagnosis of cancer," said Michael.

Breast biopsies also were more common among women taking hormones (10 percent) than among those assigned the placebo (6.1 percent), according to the study. Meanwhile, biopsies were less accurate in diagnosing cancer among women in that higher-risk group.

The hormone combination "increases breast density, which increases risk, which also delays diagnosis," Michael said.

"It's already been demonstrated, before this study, that women on combined therapy were diagnosed with cancers that were larger and at more advanced stages," Michael said. "In addition to all that, this study shows that one in 10 women had an otherwise avoidable mammogram with an abnormality. One woman in 25 had an otherwise avoidable breast biopsy."

Another significant finding showed that adverse affects persisted for at least a year after stopping medication.

Still, many women will continue to use the combined hormone therapy, Michael said.

"Women need to have a risk-benefit conversation with their physician," Michael said, and the take-home message on hormones is, "Use them for the shortest time and in the smallest amount possible."

Source: The Columbian, Vancouver, Wash. Distributed by McClatchy-Tribune Information Services. Powered by Yellowbrix.

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