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Popular antidepressant blocks breast cancer treatment

By Nigel Praities

Women taking therapies for breast cancer and antidepressants concurrently may be putting themselves at risk of death, finds a study published in the British Medical Journal.

The Canadian study in 2,500 women with breast cancer found treatment with both tamoxifen and paroxetine increased the risk of death, with the percentage risk correlating with the length of exposure to the commonly-prescribed SSRI.

Women taking paroxetine for half the time they were also taking tamoxifen had a 23% increased risk of death from any cause. This rose to 46% for those taking it for 75% of the time they were on tamoxifen.

The researchers said that the relationship was not seen with other SSRIs they studied, with a non-significant trend towards reduced breast cancer mortality in those taking venlafaxine.

Dr David Juurlink, author of the study and head of clincial pharmacology at University of Toronto, Canada, said: ‘Tamoxifen is a crucial element of therapy for patients with hormone receptor-positive breast cancer regardless of age or breast cancer stage.’

‘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.’

BMJ 2010; early online 9 Feb

Popular antidepressant paroxetine blocks breast cancer treatment