Results from a study presented at ASCO demonstrated that women who took certain antidepressant drugs while taking tamoxifen to treat their breast cancer had more than double the risk of cancer recurrence, compared with those who took tamoxifen alone. Researchers stated that this is “the first time that a comparative analysis has been done looking at various selective serotonin reuptake inhibitors [SSRIs] and what’s clear is that several of these drugs are extremely risky for women to take with tamoxifen, while others don’t present a problem.”

[ad]

The retrospective analysis examined the pharmacy and medical records for nearly 1300 women with breast cancer who were newly prescribed tamoxifen between 2003 and 2005 and who were followed up for an average of 2.7 years. The initial analysis involved one group of 353 women who were taking tamoxifen plus a moderate-to-potent CYP2D6 inhibitor, which included several types of SSRIs but was not limited to antidepressants, and a second group of 945 women who were taking tamoxifen and no CYP2D6 inhibitor.

Overall, results showed that the breast cancer recurrence rate for women using a CYP2D6 inhibitor plus tamoxifen was 13.9 percent, compared with a rate of 7.5 percent for those using only tamoxifen. Further analyses showed that the rate of recurrence for women whose treatment included use of moderate-to-potent CYP2D6 inhibitor SSRIs, such as Eli Lilly’s Prozac (fluoxetine), GlaxoSmithKline’s Paxil (paroxetine) and Pfizer’s Zoloft (sertraline), was 16 percent. In addition, data showed that those whose treatment included “weak” CYP2D6 inhibitor SSRIs, such as Forest’s Celexa (citalopram) and Lexapro (escitalopram) and Solvay’s Luvox (fluvoxamine), had a recurrence rate of 8.8 percent, which was considered to demonstrate no increase in risk for the disease.

Robert Epstein, one of the study’s authors, remarked that scientists were aware that CYP2D6 inhibitor drugs blocked the activation of tamoxifen chemically “but this is the first time there’s evidence that these drugs are putting women at a much higher risk for recurrent breast cancer.”

Popularity: 5% [?]