RecruitingClinical trialA Multicenter Prospective Observational Cohort Study Evaluating the Impact of Cancer-Directed Treatment and Medication Use, Including Cannabis Use, in Multiple Myeloma PatientsThis study assesses the impact of cannabis (also commonly called marijuana, weed, or THC) use on quality of life among patients with multiple myeloma who are receiving chemotherapy. It also evaluates the potential benefits and harms of cannabis use.