(February 8, 2010 - Insidermedicine)

Taking the antidepressant paroxetine interferes with the life-saving properties of the breast cancer therapy tamoxifen, according to research published in the British Medical Journal.
 
Here is some information about cancer and depression:
 
    •    An estimated 15 to 25% of cancer patients suffer from depression
 
    •    Depression associated with cancer can usually be treated with a combination of counseling and medication
 
    •    Depressed cancer patients should be evaluated by a professional for their risk of suicide
 
Researchers from Sunnybrook Odette Cancer Centre in Toronto and from the Institute for Clinical Evaluative Sciences (ICES) analyzed the long-term survival rates of nearly 2,500 Ontario women aged 66 and older who were treated with tamoxifen for breast cancer between the years 1993 to 2005. These women were also treated with one antidepressant of the SSRI class for some or all of the time they were taking tamoxifen.
 
Overall, about 30% of the women received antidepressant treatment while taking tamoxifen. After adjusting for factors that affect survival rates, including age, women who were taking paroxetine, which is also known under its tradename Paxil, while taking tamoxifen were more likely to die from breast cancer than those who had not taken this drug. The more paroxetine therapy overlapped with tamoxifen therapy, the higher the risk of dying from breast cancer. The authors estimate that using paroxetine for 41% of the duration of tamoxifen therapy would result in 1 additional death from breast cancer within five years for every 20 women treated. No association with breast cancer survival rates were found for other antidepressant.
 

We spoke with Dr. David Juurlink, one of the investigators of this study, who offered some further insight.

Today’s research suggests that women taking tamoxifen for breast cancer should not also take paroxetine. Never stop tamoxifen or paroxetine therapy without first consulting your health care professional