DRD2 and schizophrenia: Recent epidemiological studies found that patients with schizophrenia in which the dopaminergic pathway is activated have higher cancer risk, while the patients who received DRD2 antagonists treatment (e.g. haloperidol) have a reduced cancer risk in different solid tumors, including those of the rectum, colon, and prostate, suggesting that dopaminergic signaling pathways may be associated with the carcinogenesis of cancer [14, 32–34].