OPRM1 and cancer: In line with this assertion, genetic polymorphismsof mu opioid receptor 1 (OPRM1), which is highly colocalized withGPR151 expression in the habenula, are also associated with preoperativepain sensitivity in multiple types of cancer. Therefore, GPR151 and its variants in cancer studies may be moreaccurately attributed to cancer pain, rather than the developmentand maintenance of cancer.