Healthy Skepticism Library item: 7795

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Publication type: news

Lopatto E.
Breast Cancer Drug Stopped Early by One in Five Women
Bloomberg.com 2007 Jan 22
http://www.bloomberg.com/apps/news?pid=20601082&sid=aq.FC6MV3gsQ&refer=canada

Full text:

Jan. 22 (Bloomberg) — Patients discontinue use of tamoxifen, the most widely prescribed breast cancer drug, about twice as often as doctors thought, leading to more relapses and deaths, a study suggests.

Most women who stop using the drug are under age 40, over 75 or they have a history of antidepressant use, researchers said. About one in five women ended use of the drug within a year, the scientists found after examining prescription records in Ireland. The standard regime for the tamoxifen is five years.

Health officials expect about 180,000 new cases of breast cancer in the U.S. in 2007, and about 41,000 will die from the disease, according to the National Cancer Institute Web site. Tamoxifen, aimed at stopping disease recurrence, can lessen symptoms, causing some patients to think it is okay to drop the drug, the researchers said. The study suggests more women may survive the disease if they comply with pill schedules.

``We think we have identified risk factors so that doctors can watch certain patients more closely,’‘ the lead author, Thomas Barron, a research fellow at Trinity college in Dublin, said in a Jan. 19 telephone interview. The study, released early online, will be published March 1 in the journal Cancer.

Tamoxifen, a generic medicine, is prescribed to three of every four women diagnosed with breast cancer diagnosis, Barron said. In contrast to other studies on the drug’s use, this research didn’t rely on self-reporting by patients, which is less reliable than prescription records, Barron said.

Five-Year Regime

The medicine is designed to be taken over five years as an adjunct to chemotherapy or surgery. It improves by 47 percent the 10-year survival rate of women diagnosed with breast cancer, according to an overview of randomized trials published in Lancet in May 1998. Women at high risk for breast cancer who took tamoxifen had a 49 percent decrease in cancer diagnosis, said a study conducted by the National Cancer Institute

The new study, by design, shed no new light on the reasons women stop using the drug, the researchers said.

``It is doubtful that the full benefits of tamoxifen, as demonstrated in randomized studies, will be achieved in clinical practice,’‘ the Trinity scientists wrote in the new study, citing discontinuance patterns.

Because stopping medication increases the death rate, the Trinity researchers said efforts to spur compliance with pill schedules ``may be worthwhile’‘ in breast cancer patients.

Children

Some women under 40 may stop taking the medicine because they want to have children, said Clifford Hudis, the chief of breast cancer medicine at Memorial Sloan-Kettering Cancer Center, in New York, in a Jan. 19 telephone interview. Taking the drug during pregnancy can harm fetuses, according to the National Cancer Institute.

Breast cancer that originates in the breast may spread to other parts of the body in a process known as metastasis. To prevent the cancer’s spread, patients — who may also undergo surgery — are given drugs, such as tamoxifen.

Some past studies have shown that women who take antidepressants such as Eli Lilly & Co.‘s Prozac or GlaxoSmithKline Plc’s Paxil for hot flashes during menopause have worse results on tamoxifen therapy.

Research suggests the active ingredients in these antidepressants prevents the body from using the cancer drug effectively, said David Flockhart, a professor of medicine and genetics at Indiana University School of Medicine in Indianapolis, in an Oct. 16 telephone interview. As a result, many oncologists prescribe different types of antidepressants, such as Wyeth’s Effexor, for women on tamoxifen, Flockhart said.

Off Patent in 2003

Tamoxifen was marketed under the brand name Nolvadex by AstraZeneca Plc, based in London. The company no longer distributes the drug in the U.S., as the patent ran out in 2003, said Kirsten Evraire, a company spokeswoman.

Barr Pharmaceuticals Inc., based in Woodcliff Lake, New Jersey; Teva Pharmaceutical Industries Ltd., based in Petah Tikvah, Israel; Mylan Laboratories, based in Canonsburg, Pennsylvania; and the Andrx unit of Corona, California-based Watson Pharmaceuticals Inc. all have FDA permission to market the drug in the U.S., according to the agency’s Web site.

To contact the reporter on this story: Elizabeth Lopatto in New York at elopatto@bloomberg.net