A new analysis finds that women in New Jersey who take the breast cancer drug tamoxifen in conjunction with certain popular antidepressants may be at a higher risk for a breast cancer recurrence.
In May, Medco Health Solutions, Inc. and Indiana University School of Medicine released a study revealing that women using tamoxifen to prevent a recurrence of breast cancer who also use certain selective serotonin reuptake inhibitors (SSRI), for example Prozac (fluoxetine), Paxil (paroxetine) and Zoloft (sertraline), have up to twice the chance of having a recurrence of the disease.
In a separate New Jersey-specific analysis, Medco found that among nearly 2,000 tamoxifen patients in the state during 2008, 12 percent were also taking SSRIs, including those that could put them in the at-risk population.
“We’ve been aware that certain antidepressants, known as CYP2D6 inhibitor drugs, block the activation of tamoxifen chemically, but this evidence shows that these drugs are putting women in New Jersey and across the nation at a much higher risk for recurrent breast cancer,” said Dr. Milayna Subar, National Practice Leader for Medco’s Oncology Therapeutic Resource Center located at Medco’s Willingboro, N. J. pharmacy. “Women taking tamoxifen along with an SSRI should speak with their doctor immediately to discuss modifications to their medication regimen to ensure they are getting the full benefit of their tamoxifen therapy.”
Approximately 500,000 women take tamoxifen in the U.S., with 80,000 new patients starting on the treatment annually. Nearly 30 percent of women taking tamoxifen also use an antidepressant. Based on estimates from the Centers for Disease Control and Prevention, New Jersey is among the states with the highest breast cancer incidence and death rate in the country.
The study by Medco and Indiana University School of Medicine that was presented at the 2009 Annual Meeting of the American Society of Clinical Oncology (ASCO). It was the largest study to-date looking at how these drugs impact breast cancer recurrence rates when taken with tamoxifen.
Antidepressants are often prescribed when women receiving tamoxifen are depressed, or to treat hot flashes — a common side effect of the breast cancer drug. Paxil, Prozac and Zoloft are among a group of antidepressant drugs known as CYP2D6 inhibitors. These drugs prevent the CYP2D6 enzyme from working properly, and cause less of the active form of tamoxifen, called endoxifen, from being produced, making the drug less effective at preventing breast cancer. Women taking tamoxifen along with certain SSRIs have a 2-fold increased risk of breast cancer recurrence compared to women not taking these drugs together.
Tamoxifen
Tamoxifen is one of the oldest and most widely used treatments for reducing the risk of breast cancer recurrence among women with estrogen-dependent tumors. The drug works by blocking the estrogen receptors in the breast cells and can reduce the risk of a breast cancer recurrence by up to 50 percent. It’s the only anti-estrogen available for prevention of breast cancer recurrence in pre-menopausal women and is one of several anti-estrogens used to treat post-menopausal breast cancer patients.
Source: Medco Health Solutions, Inc.