Paxil May Increase Breast Cancer Risk


The antidepressant Paxil may be one of the more common selective serotonin reuptake inhibitors, or SSRIs, but it may also be one of the risk factors contributing to breast cancer, according to a new study reported by the Los Angeles Times today.  The study was undertaken by City of Hope Hospital in Duarte, California.  Interestingly enough, it was a mere decade ago when Harvard Health Publications from Harvard Medical School said that Paxil did not contribute to the occurrence of breast cancer.

Paxil has been considered an effective method to reduce hot flashes in menopausal women.  Menopausal or postmenopausal women have long said that hot flashes are not a welcome symptom of menopause, and often would like to avoid hormone therapy as a method of coping with menopause.  Past studies have shown that hormone therapy can contribute to breast cancer risk.  However, SSRIs can also stimulate the prolactin levels, which kickstarts the growth of certain breast cells.  As a result, there’s been an increased level of concern about Paxil for some time.  It’s only been with this recent study that it has been shown that the antidepressant does, indeed, contribute to breast cancer risk.

Paxil has a weak estrogenic effect, which means that it could have some responsibility in the occurrence of some cancers in women.  The popular antidepressant was compared to another 445 drugs on the market that are, like Paxil, in wide circulation.  The study’s findings came about after the development of faster methods in determining which drugs can have a disruptive effect on the hormone balance in the human body.

By contrast, certain antifungals, such as biconazole and oxyconazole, could have some responsibility in preventing certain cancers in women.  The findings about Paxil and the antifungals build upon a 2010 Canadian study which found that women who take Paxil in addition to tamoxifen hormone therapy – a commonly prescribed therapy following breast cancer surgery – increased their risk of dying of breast cancer by a significant margin.

It’s been estimated that roughly 25 percent of women who are undergoing breast cancer treatment are also struggling with depression and may be prescribed antidepressants such as Paxil to cope.  In addition, Paxil has been found in a 2012 study from Holland to potentially contribute to a greater risk of falling among elderly patients on the antidepressant.

Paxil may contribute to an increased risk of breast cancer because of its weak estrogenic effect, particularly since it’s been noted that estrogen levels play a significant contributory role in the development of the disease.  Women who struggle with depression as a result of breast cancer treatment or diagnosis and are also on Paxil to cope are facing a greater risk of dying from the disease, according to the study.  It’s believed that this is because paroxetine – the chemical name for Paxil – may block a liver enzyme that may aid in the metabolism of tamoxifen, the hormone therapy commonly prescribed in post-breast cancer surgery patients.  Researchers, however, note that the study didn’t prove conclusively whether or not paroxetine alters estrogen activity directly or indirectly.

By Christina St-Jean


LA Times

Raw Story

Harvard Health Publications

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