Medical Marijuana Use in a Community Cancer Center.

PURPOSE: The primary purpose of this study was to compare the incidence of marijuana use between patients with early- versus advanced-stage cancers. Differences in adverse effects, drug-drug interactions, and drug-disease interactions between those who use marijuana and those who do not were also compared.

METHODS: Patients age 18 years and older who were receiving chemotherapy were asked to complete an electronic self-reported questionnaire. In addition to questions about patient demographics, current adverse effects, cancer type and stage, comorbidities, performance status, treatment regimen, and general marijuana use, those patients who used marijuana within the last 30 days (current marijuana users) were asked additional questions about the route and frequency of marijuana administration, about reason(s) for use, about possession of a marijuana card, and if they had received any counseling about marijuana. Drug-drug and drug-disease interactions were also analyzed.

RESULTS: The overall incidence of marijuana use was 18.3% (32 of 175 patients). The incidence of marijuana use in patients with early- versus advanced-stage cancers was 19.6% (11 of 56 patients) versus 17.6% (21 of 119 patients; P = .75). Patients who use marijuana reported more pain, nausea, appetite issues, and anxiety. There were more drug-drug interactions associated with marijuana use, primarily with concurrent CNS depressants. The frequency of drug-disease interactions between those who use marijuana versus those who do not was similar.

CONCLUSION: Approximately one in five patients with cancer who were receiving chemotherapy were using marijuana, and the frequency was equal in early- and advanced-stage cancer groups. The risks versus benefits should be discussed with all patients who use marijuana.