Ending hormore therapy tied to lower cancer risk

CHICAGO — Two studies released Wednesday suggest that going off hormone therapy significantly reduces a woman's chances of developing ovarian cancer as well as breast cancer.

An update of the landmark Million Women Study found that taking hormones caused a small but significant increase in the risk of ovarian cancer among postmenopausal British women. But their risk returned to normal after they went off the medications.

Meanwhile, an extended analysis of U.S. breast cancer rates reinforced the notion that the recent decrease in the number of women diagnosed with that disease was caused by the drop in the use of hormone therapy.

Doctors noted the cancer risk from hormones is very small, and hormone therapy is still right for some women.

Researchers announced in December that breast cancer diagnoses in this country dropped by nearly 7 percent in 2003 after rising steadily for two decades and then leveling off. The decline from the previous year was about 15 percent in women older than 50, the group most likely to have been taking hormones before a well-publicized federal warning in 2002 scared millions of them into stopping.

In this week's New England Journal of Medicine, the same research team added data from 2004, which showed that the incidence of breast cancer remained at about the same level as the year before — the lowest level in 20 years.

"We all were worried it was going to be a one-year wonder — that stopping hormone therapy would result in a dip for one year and then the levels would go back up," said Dr. Peter Ravdin of the University of Texas. "It turns out that in 2004 the decline didn't deepen but it was maintained, which is kind of nice. That's 16,000 women a year who didn't get breast cancer."

Ravdin and his colleagues stressed their analysis does not prove the drop in breast cancer cases was caused by women abandoning hormone therapy, but the circumstantial evidence is compelling.

"It's a smoking gun that's really smoking," said Donald Berry, senior investigator on the New England Journal paper. "Nothing else can explain it."

The decline began in mid-2002 and leveled off after 2003, the researchers found, using data collected from the regional registries of the National Cancer Institute. The Women's Health Initiative — a huge, federally funded trial of hormone therapy — reported in July of 2002 that hormone therapy increased the risk of breast cancer and heart disease. Within months, use of hormones by U.S. women plummeted by about 50 percent.