Some antipsychotic drugs may hike breast cancer risk

Antipsychotic medications are frequently prescribed for women with autism, but new research suggests that some of these drugs may significantly increase a woman’s risk for breast cancer.

Noting that a number of antipsychotic drugs increase levels of the hormone prolactin—which can lead to menstrual cycle irregularities, abnormal breast milk production, and abnormal breast tissue growth— Tahir Rahman and colleagues investigated the possibility that these drugs might affect women’s risk for breast cancer as well. The researchers used data collected from 2012 through 2016 on 540,737 women between the ages of 18 and 64 who took antipsychotics. They investigated three categories of antipsychotic medications:

• Drugs associated with high prolactin levels, such as haloperidol, paliperidone, and risperidone.
• Drugs with “mid-range” effects on prolactin, including iloperidone, lurasidone, and olanzapine.
• Drugs with a smaller effect on prolactin levels, such as aripiprazole, asenapine, brexpiprazole, cariprazine, clozapine, quetiapine, and ziprasidone.

The researchers compared the effects of all three categories of antipsychotic drugs to the effects of anticonvulsant drugs and lithium, which also are often prescribed to treat psychiatric disorders. When compared with these types of drugs, the relative risk of breast cancer was 62% higher for women who took antipsychotic drugs associated with high levels of prolactin and 54% higher for those taking antipsychotic drugs with “mid-range” effects. Antipsychotics that had little effect on prolactin were not associated with any increase in breast cancer risk.

Rahman says, “Our study confirms findings from a smaller European study that advised women and their doctors to first try drugs that don’t affect prolactin levels. We agree with that advice and believe psychiatrists should start to monitor prolactin levels in their patients taking antipsychotics.”

Editor’s note: Since antipsychotics can cause enlargement of the breast tissue in men (gynecomastia), it is possible that these drugs may also increase males’ risk for breast cancer. This issue needs to be examined.

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“Risk of breast cancer with prolactin elevat ing antipsychotic drugs: An observational study of US women (ages 18-64 years),” Tahir Rahman, John M. Sahrmann, Margaret A. Olsen, Katelin B. Nickel, J. Phillip Miller, Cynthia Ma, and Richard A. Grucza, Journal of Clinical Psychopharmacology, December 3, 2021 (online). Address: Tahir Rahman, Department of Psychiatry, Washington University in St. Louis, 660 S Euclid Ave, Campus Box 8134, St. Louis, MO 63110, trahman@wustl.edu.

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“Antipsychotic drugs may increase risk of breast cancer,” news release, Washington University School of Medicine in St. Louis, December 9, 2021

This article originally appeared in Autism Research Review International, Vol. 36, No. 1, 2022