Tracking medications provided to over a half million U.S. women, researchers at Washington University School of Medicine in St. Louis have found that many commonly prescribed older antipsychotic medications, and some newer ones, are associated with a significant increase in risk of breast cancer. Antipsychotics are prescribed for a broad range of conditions, including depression, bipolar disorder, schizophrenia, dementia and autism spectrum disorders.
While earlier studies have uncovered links between antipsychotic drug use and breast cancer risk, this is the first study to compare newer antipsychotics to older drugs, and to look at how the drugs affect levels of a hormone called prolactin. Increased levels of prolactin have been associated with breast cancer.
Prolactin is an important hormone involved in puberty, pregnancy and breastfeeding. However, many antipsychotics elevate prolactin levels and can produce side effects such as menstrual cycle irregularities, abnormal breast milk production and abnormal breast tissue growth.
The findings will be published in the February issue of the Journal of Clinical Psychopharmacology but are available online.
“Many women with psychiatric illnesses such as schizophrenia and bipolar disorder will take antipsychotics for decades, and they are essential to keeping symptoms in check,” said the paper’s first author, Tahir Rahman, MD, associate professor of psychiatry. “But both older antipsychotic medicines and some newer drugs raise levels of prolactin and increase the risk of breast cancer, which is concerning. 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.”