Schizophrenia drugs may increase breast cancer risk, finds Lancet study

According to a new study conducted by Heidi Taipale and his colleagues, the use of antipsychotics that boost prolactin levels is strongly related with an elevated risk of breast cancer in women with schizophrenia. The findings of this study were published in the Lancet Journal of Psychiatry on 30th August, 2021.

Breast cancer is more prevalent in female schizophrenia patients than in the general population. It is unclear if therapy with prolactin-inducing antipsychotics increases the risk of breast cancer. In this study the researchers attempted to shed a light on the use of antipsychotic drugs and its association with the risk of breast cancer.

Nested case-control research was conducted using Finnish national records of hospitalization, prescription medication purchases, and cancer diagnoses. Women with schizophrenia who had breast cancer (cases) were matched with five women who did not have cancer based on age and length of disease (control). The major focus of the study was the relationship between cumulative exposure to prolactin-inducing medications and breast cancer. The studies were carried out using conditional logistic regression, with comorbid conditions and concomitant medicines taken into account.

Key Findings:

o Between 1972 and 2014, 30 785 women were diagnosed with schizophrenia, and 1069 were diagnosed with breast cancer between January 1, 2000, and December 31, 2017.

o In comparison to limited exposure (one year), 1–4 years cumulative exposure or 5 or more years exposure to prolactin-sparing antipsychotics was not linked with an elevated incidence of breast cancer in a study of 5339 matched controls.

o When compared to less than one year of exposure to prolactin-increasing antipsychotics (all other antipsychotics), 1–4 years of exposure was not linked with an elevated risk, while exposure for 5 or more years did.

o Long-term use of prolactin-increasing antipsychotics was related with a greater risk of developing lobular adenocarcinoma than ductal adenocarcinoma.

In conclusion, Long-term exposure to prolactin-increasing antipsychotics, but not to prolactin-sparing antipsychotics, is related with an elevated risk of breast cancer. In women with schizophrenia who are on prolactin-increasing antipsychotics, it is critical to monitor prolactinemia and manage hyperprolactinemia.

References:

Heidi Taipale, Marco Solmi, Markku Lähteenvuo, Antti Tanskanen, Christoph U Correll, Jari Tiihonen, Antipsychotic use and risk of breast cancer in women with schizophrenia: a nationwide nested case-control study in Finland, https://doi.org/10.1016/S2215-0366(21)00241-8.