Despite the increase of cannabis use to face symptoms associated with cancer, there is still a lack of dosage information for medical professionals. Recent studies involving 4,000 oncology patients treated with medical cannabis reported relevant improvements in cancer-associated issues such as pain, nausea, and anxiety feelings while reducing opioids, antidepressants and other supportive treatments. 
Well-designed, randomized trials are necessary to scientifically evaluate and assess the best formulation, dosages, routes of administration, safety, and efficacy of cannabis treatments in current anti-cancer therapeutics including chemotherapy, targeted therapy, and immunotherapy.  Many challenges have to be overcome to incorporate medical cannabis into clinical oncology practices and often difficulties are linked to the submission of investigational new drug applications, directives for the proper handling and storage conditions, ensuring research funding, the acquisition of schedule I Drug Enforcement Agency licences, and the obtaining of research-grade cannabis in collaboration with the National Institute of Drug Abuse (NIDA).
A pilot randomized controlled trial was recently performed on stage IV cancer patients requiring opioid medications.  The participants were divided into early- versus delayed-start cannabis to assess the impact of tetrahydrocannabinol (THC) and cannabidiol (CBD) on cancer-induced pain and opioid use, the suggested dose escalation strategy, the feasibility of conducting interventional trials with state-sponsored cannabis programs, and to determine the overall patient satisfaction.
After being inscribed to the Minnesota Medical Cannabis Program (MMCP), patients were advised to begin dosing at 2.5-5 mg/2.5-5 mg of THC/CBD daily and increasing up to 30-40 mg of THC and identical amounts of CBD as maintainance dose over 2-4 weeks. The average daily doses of THC and CBD were 34 mg and 17 mg, respectively.
The feasibility of the research was evaluated by considering the number of patients screened and enrolled to the MMCP. Patients completed surveys on pain levels, opioid and medical cannabis use, side effects, and overall satisfaction of the study at different time points of treatment. During the trial period, no serious cannabis-related adverse effects were reported to the research call center and only a few patients were uncomfortable with the unwanted sensations related to the psychotropic effect of THC.
Even if cannabis dosing will remain individualized, this pilot study provided a guide for dosing goals which can be further implemented through symptom-targeted trials. In the study, patients could use different cannabis-derived products and administration routes; this variability constitutes a limitation for the reproducibility and the generalization of the research results.
Nevertheless, incorporating cannabis into routine cancer care could remarkably improve pain control and minimize opioid requirements. Additional studies and robust evidence is needed to effectively introduce cannabis into treatment plans, and properly and safely guide oncology patients. Larger study cases on cancer patients with similar medical conditions are essential to disclose the real benefits and risks associated with medical cannabis use.
References: Bar-Lev Schleider L, Mechoulam R, Lederman V, et al. Prospective analysis of safety and efficacy of medical cannabis in large unselected population of patients with cancer. Eur J Intern Med. 2018;49:37-43. [journal impact factor = 4.329; times cited = 116]
 Zylla DM, Eklund J, Gilmore G, et al. A randomized trial of medical cannabis in patients with stage IV cancers to assess feasibility, dose requirements, impact on pain and opioid use, safety, and overall patient satisfaction. Support Care Cancer. 2021;29(12):7471-7478. [journal impact factor = 3.603; times cited = 2]