Breast Cancer Risk Drops One Year After End of Hormone Therapy

Women whose breast cancer risk increased after they took Wyeth’s hormone-replacement pill Prempro had their likelihood of cancer return to normal a year after ceasing therapy, a study found.
The number of breast cancer diagnoses dropped 28 percent within the first year after hormone therapy ended, researchers said in the New England Journal of Medicine.

The report supports a 2007 finding that decreased use of Wyeth’s hormone drugs, starting in 2002, is the most likely explanation for a 6.7 percent drop in U.S. breast cancer diagnoses in 2003. Millions of menopausal women abandoned the hormones after a landmark study tied Prempro to heart disease and cancer.

“The good news is that if you discontinue hormones, your risk drops pretty quickly,” said Marcia Stefanick, a professor of medicine at Stanford University in California and an author of the study. “We know nationwide, breast cancer rates dropped within a year of the initial publication. We now have good evidence that, yes, this happened absolutely in association with the drop of the hormones.”

Wyeth’s Prempro is a combination of estrogen and progestin.

The study “does not support the theory that the decline in HT use, specifically estrogen-plus-progestin use, caused the one-time abrupt nationwide decline in breast cancer incidence,” wrote Gwendolyn Fisher, a spokeswoman for Madison, New Jersey- based Wyeth, in an e-mailed statement. “The authors concede that this explanation remains controversial.”

Mammography

The decline in cancer may be due to an increase in mammography during the 1990s, which led to identifying a large number of cancers, Fisher wrote. This meant that fewer cases would be found later, after the glut of new cancers detected by a new screening technology. Such a phenomenon has been observed with other screening tests, Fisher wrote.

The breast cancer declines started in mid-2002, shortly after a study known as the Women’s Health Initiative was released, researchers wrote in April 2007 in the New England Journal of Medicine. The drop started to flatten out after about a year, with a 6.7 percent total decline in 2003. The rate for 2004 stayed at the lower level, the report said.

Decline Debated

“There was a controversy about the decline in breast cancer after WHI,” said JoAnn Manson, a professor at Harvard Medical School in Boston and an author of the latest study. After disagreements emerged over the cause of the decline, researchers scrutinized women in two groups.

“In both study populations, the risk decreased rapidly after stopping hormone therapy, and in neither case was it explained by changes in mammogram screening,” Manson said.

For today’s report, researchers analyzed data from both groups. One was the approximately 15,000 women who were in the original WHI trial, which was halted early when patients on the hormones were diagnosed with cancer more often than those getting a placebo. They also collected data from 41,000 women enrolled in a separate study that began in 1994.

“The great thing about this report is that it had individual women, and the randomized element,” said Donald Berry, a biostatistician at the University of Texas M.D. Anderson Cancer Center in Houston, the author of the 2007 New England Journal study. “That adds credibility.”

Risk Analyzed

The original WHI study found that women who were on the hormone-replacement drug for at least five years showed a doubled risk of breast cancer each year they continued it.

The current report didn’t examine whether the cancers were estrogen-receptor positive or negative, Berry said. His research found that much of the growth of breast cancer was due to tumors fueled by estrogen.

After the initial study report, use of Wyeth’s hormone replacement therapies Prempro and Premarin plummeted. The 61 million prescriptions written in 2001 fell to 47 million in 2002, 27 million in 2003, 21 million in 2004 and 18 million in 2005.

Wyeth emphasized redirecting hormone therapy to younger women, mostly for treating the symptoms of menopause, with additional stress on the guidance to use the hormones for “a short period of time,” said Joseph Camardo, the senior vice president for global medical affairs at Wyeth.

“What’s interesting to me is that six years later, this advice still applies,” Camardo said.

Wyeth is defending itself against 8,700 legal actions brought by about 11,000 women in “various federal and state courts,” in the U.S. over allegations that their breast cancer, stroke, heart attack, ovarian cancer or heart disease stemmed from the use of Wyeth hormones, according to a company regulatory filing.