New studies link cancer risk, hormone use

ATLANTA – Research on two continents signaled more bad news for menopause hormones, offering the strongest evidence yet that they can raise the risk of breast cancer and are tied to a slightly higher risk of ovarian cancer.

New U.S. government numbers showed that breast cancer rates leveled off in 2004 after plunging in 2003 – the year after millions of women stopped taking hormones because a big study tied them to higher heart, stroke and breast cancer risks. Experts said the leveling off shows that the 2003 drop in the cancer rate was real and not a fluke.

From 2001 to 2004, breast cancer rates fell almost 9 percent – a dramatic decline, researchers report in today’s New England Journal of Medicine. The trend was even stronger for the most common form of the disease – tumors whose growth is fueled by hormones. Those rates fell almost 15 percent among women ages 50 to 69, the group most likely to have been on hormone pills.

At the same time, a study of nearly 1 million women in the United Kingdom showed that those who took hormones after menopause were 20 percent more likely to develop ovarian cancer or die from it than women who never took the pills. That study was published online by the London-based journal the Lancet.

For consumers, the new research doesn’t change the advice to use the lowest dose for the shortest time possible for hot flashes and other menopause symptoms that can’t otherwise be controlled.

For cautious scientists, the new breast cancer numbers were more evidence of the hormone-breast cancer link.

“The story has gotten stronger,” said Dr. Peter Ravdin, a biostatistician at the University of Texas M.D. Anderson Cancer Center in Houston who led the research.

Some were skeptical several months ago when Ravdin and National Cancer Institute researchers first reported the 2003 drop in the breast cancer rate. The new numbers, which add 2004, prove this was no fluke, said Dr. Julie Gralow, a spokeswoman for the American Society of Clinical Oncology and cancer expert at the University of Washington in Seattle.

After rising steadily through the 1990s, the breast cancer rate dipped from 2001 to 2002, from 138 cases to 135 cases per 100,000 women. After the federal Women’s Health Initiative study reported in July 2002 on the health risks of hormones, use of the pills plunged.

So did the breast cancer rate the following year – to 126 cases per 100,000 women. It was the steepest fall since the government started keeping records in the 1970s. The 2004 rate held steady at about 126 cases per 100,000.

Wyeth Pharmaceuticals, which makes top-selling hormone pills Prempro and Premarin, criticized the study as overly speculative. Company spokesman Dr. Joseph Camardo said hormone prescriptions continued to fall in 2004 but breast cancer rates did not decline proportionately.