Drug abuse is the use of drugs in amounts or by methods that is harmful for the health. Drug use disorders (DUD) are associated with a range of adverse health outcomes including increased mortality rates [1, 2]. For example, patients in opioid substitution treatment (OST) are shown to have significantly higher non-drug-related mortality including Cancer than the general population [3, 4]. According to the American Cancer Society, substance abuse and addiction make up about 30% of all cancer deaths. In this review article we tried to summarize that drug abuse disorders are risk factors for Cancers.