Featured Research

from universities, journals, and other organizations

Popular antidepressant blocks the beneficial effects of tamoxifen in breast cancer

Date:
February 10, 2010
Source:
BMJ-British Medical Journal
Summary:
Women with breast cancer who take the antidepressant paroxetine at the same time as tamoxifen are at an increased risk of death, concludes a new study.

Women with breast cancer who take the antidepressant paroxetine at the same time as tamoxifen are at an increased risk of death, concludes a study published on the British Medical Journal website.

Related Articles


However, the authors stress that their results should not lead patients to stop taking tamoxifen, and do not imply that paroxetine itself causes or influences the course of breast cancer. "This is simply a situation in which paroxetine impairs the effectiveness of tamoxifen," they explain.

Breast cancer is the most commonly diagnosed cancer in women worldwide and the drug tamoxifen significantly improves survival. In order to work, however, tamoxifen must be converted into an active metabolite (endoxifen) by the liver.

But some drugs can interfere with this process. Antidepressants are of particular importance because they are commonly used in women with breast cancer, often for long periods of time. Although many antidepressants have little or no impact on tamoxifen's metabolism, paroxetine, a member of the selective serotonin reuptake inhibitor (SSRI) class of drugs, is a potent inhibitor of the metabolic step that converts tamoxifen to endoxifen.

So Dr Catherine Kelly and colleagues at the Institute for Clinical Evaluative Sciences (ICES) in Toronto set out to investigate whether SSRIs can reduce tamoxifen's effectiveness in practice.

They examined the healthcare records of 2,430 women aged 66 years or older with breast cancer who received tamoxifen between 1993 and 2005. About 30% of these women also received an antidepressant at some time during their treatment with tamoxifen, and paroxetine was the most commonly used agent.

The results show that use of paroxetine, but not other SSRIs, in combination with tamoxifen, was associated with an increased long-term risk of breast cancer death, in a fashion that correlated with the extent of drug overlap.

This supports the theory that paroxetine can reduce or abolish the benefit of tamoxifen in women with breast cancer.

The researchers estimate that treatment with paroxetine for 41 percent of the total time on tamoxifen (the median in this study) will result in one additional breast cancer death at five years for every 20 women so treated. The risk with more extensive overlap is greater.

"Our findings indicate that the choice of antidepressant can significantly influence survival in women receiving tamoxifen for breast cancer," says Dr David Juurlink, one of the study's authors and a scientist at ICES. "This observation is consistent with what we know about tamoxifen's metabolism. These results highlight a drug interaction that is extremely common, widely underappreciated and potentially life-threatening, yet uniformly avoidable."

"Tamoxifen is a crucial element of therapy for patients with hormone receptor-positive breast cancer regardless of age or breast cancer stage," he adds. "When co-prescription of tamoxifen with an antidepressant is necessary, preference should be given to antidepressants that exhibit little or no impact on tamoxifen's metabolism."

In an accompanying editorial, Frank Andersohn and Stefan Willich from Charitι University Medical Center in Berlin say that clinicians should avoid co-prescribing paroxetine and tamoxifen in women with breast cancer, but warn against abrupt withdrawal of SSRI treatment.

They also call for this potential interaction to be made clear on all products containing tamoxifen and paroxetine, and for its promotion amongst physicians and pharmacists.


Story Source:

The above story is based on materials provided by BMJ-British Medical Journal. Note: Materials may be edited for content and length.


Cite This Page:

BMJ-British Medical Journal. "Popular antidepressant blocks the beneficial effects of tamoxifen in breast cancer." ScienceDaily. ScienceDaily, 10 February 2010. <www.sciencedaily.com/releases/2010/02/100209182454.htm>.
BMJ-British Medical Journal. (2010, February 10). Popular antidepressant blocks the beneficial effects of tamoxifen in breast cancer. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2010/02/100209182454.htm
BMJ-British Medical Journal. "Popular antidepressant blocks the beneficial effects of tamoxifen in breast cancer." ScienceDaily. www.sciencedaily.com/releases/2010/02/100209182454.htm (accessed October 25, 2014).

Share This



More Health & Medicine News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

IKEA Desk Converts From Standing to Sitting With One Button

IKEA Desk Converts From Standing to Sitting With One Button

Buzz60 (Oct. 24, 2014) — IKEA is out with a new convertible desk that can convert from a sitting desk to a standing one with just the push of a button. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Ebola Protective Suits Being Made in China

Ebola Protective Suits Being Made in China

AFP (Oct. 24, 2014) — A factory in China is busy making Ebola protective suits for healthcare workers and others fighting the spread of the virus. Duration: 00:38 Video provided by AFP
Powered by NewsLook.com
WHO: Millions of Ebola Vaccine Doses by 2015

WHO: Millions of Ebola Vaccine Doses by 2015

AP (Oct. 24, 2014) — The World Health Organization said on Friday that millions of doses of two experimental Ebola vaccines could be ready for use in 2015 and five more experimental vaccines would start being tested in March. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Doctor in NYC Quarantined With Ebola

Doctor in NYC Quarantined With Ebola

AP (Oct. 24, 2014) — An emergency room doctor who recently returned to the city after treating Ebola patients in West Africa has tested positive for the virus. He's quarantined in a hospital. (Oct. 24) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins