Some factors to be considered for prescribing NOACs in cancer patients receiving chemotherapies are; (i) investigation of drug-drug interaction, (ii) etiologies of thrombocytopenia, (iii) severity of cancer patients, (iv) risk of bleeding events, (v) elderly patients, (vi) renal impairment, (vii) interactions with CYP3A4 and p-glycoprotein, and (viii) medication history and a majority of other complications that need to be monitored [5,26,29]. The gene discussed is CYP3A4; the disease is cancer.