Data elements extracted were manuscript information (journal, title, authors, and year), study type (clinical [human subjects], including ex vivo), preclinical (in vivo [animal model] or in vitro), malignancy (type, subtype, model, or cell line), ligand (μOR agonist [ie, most analgesic opioids], antagonist, and partial agonist) and concentration information (eg, IC50), any coinciding antineoplastic treatment, and predominant effect reported (ie, promotion or inhibition of tumor growth or chemotherapeutic activity). Here, OPRM1 is linked to neoplasm.