Breast Cancer Side Effects Linked to Antipsychotic Medications: Study

The findings of a new study suggest that side effects of antipsychotic medications may increase the risk of breast cancer by as much as 35%, with some particular drugs, such as Risperdal, Haldol, and Invega, causing even greater impact.

Researchers with the Washington University School of Medicine in St. Louis found a link between the antipsychotic drugs and how they affect the hormone prolactin, which they say can significantly increase the chance of breast cancer for women. Those drugs which generated the highest levels of prolactin, known as Category 1 antipsychotics, were linked to the largest increased breast cancer side effects.

Their findings were published online in the Journal of Clinical Psychopharmacology on December 3, and will appear in print in the February 2022 issue.

The researchers used IBM MarketScan Commercial and Medicaid Databases, comparing women taking antipsychotics to those taking anticonvulsants or lithium. Out of data involving more than 540,000 women, a total of 914 cases of invasive breast cancer were identified.

According to their findings, exposure to any antipsychotic was associated with a 35% increased risk of breast cancer. However, Category 1 drugs, like Risperdal and Sustenna, which resulted in high prolactin levels, were linked to a 62% increased risk. Category 2 drugs, like Fanapt, Latuda and Zyprexa, were associated with a 54% increased risk of breast cancer, while Category 3 antipsychotics did not appear to increase the risk of a breast cancer diagnosis at all.

“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,” lead author Tahir Rahman, an associated professor of psychiatry, said in a Washington University press release. “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.”

In August, Finnish researchers published a study in The Lancet, which found a strong relationship between the use of prolactin-increasing antipsychotics and the development of lobular adenocarcinoma; a form of breast cancer.

While antipsychotics have become increasingly popular, past studies have shown antipsychotic drugs have serious potential side effects, including reduced alertness, decreased blood pressure, increased risk of diabetes and heart disease, and even movement disorders that resemble those seen in Parkinson’s.

In January 2019, a study published in the medical journal JAMA Psychiatry, found children and young adults taking antipsychotic faced an increased risk of sudden death from cardiovascular or metabolic causes.

A 2016 study published in the May issue of JAMA Neurology found the mortality rates of patients with Parkinson’s disease who took antipsychotics were much higher compared with matched patients. The study highlighted the risks many nursing home residents face from being given antipsychotics as a form of chemical restraint.