Antipsychotic treatment, prolactin, and breast tumorigenesis.

BACKGROUND Over the last decades prolactin (PRL) has gained attention for its possible role in breast tumorigenesis. As all antipsychotics (although differences with respect to PRL elevation are large) have the propensity to induce hyperprolactinemia (HPRL), questions have arisen concerning the influence of PRL-elevating antipsychotic medications on breast cancer risk. SUBJECTS AND METHODS A literature search (until January 2016), using the MEDLINE database, was conducted for English-language published clinical studies to identify and synthesize data of the current state of knowledge concerning the relationship between HPRL, breast cancer risk (factors) and antipsychotic medication. RESULTS Results of human prospective studies evaluating the relationship between pre-diagnostic circulating PRL levels and breast cancer risk are limited, equivocal and only correlational. Associations between higher circulating PRL levels and other breast cancer risk factors than nulliparity and hormone therapies mostly have been negative for both pre-and postmenopausal women. Until today, no causal link between (chronic) administration of antipsychotics and breast tumorigenesis in humans has been demonstrated. Finally, several reports describe mechanisms of cancer protection with the PRL hormone as well as with antipsychotic medication. CONCLUSION The role of PRL in breast carcinogenesis therefore remains unclear, unconfirmed, yet controversial. Antipsychotics should not be withhold for breast cancer prevention reasons to patients in need of this sometimes life-saving medication, even if classical breast cancer risk factors are present.