The largest review of medical cannabis for cancer, published this week in Frontiers in Oncology, shows a 75% scientific consensus that cannabis can both alleviate cancer‑related symptoms and directly inhibit tumor growth.
Study scope and methodology
Lead author Ryan Castle, research director at the Whole Health Oncology Institute, said the analysis examined more than 10,000 peer‑reviewed studies — ten times the sample size of any previous review.
By applying natural language processing to assess sentiment, the team quantified how many papers viewed cannabis as positive, neutral or negative for treating cancer or its symptoms.
Findings reveal strong agreement
Seven‑quarters of the studies reported positive outcomes for cannabis in reducing inflammation, boosting appetite and easing nausea, and a clear majority indicated direct anti‑cancer effects such as cell death and slowed proliferation.
Expert reactions
Castle said the 75‑25 split far exceeded the moderate consensus he had anticipated, calling the level of agreement “shocking” for a controversial topic.
Oncologist Donald Abrams of UCSF, who has treated patients with cannabis for decades, remains skeptical about cancer‑curing claims despite acknowledging symptom‑relief benefits.
“I have seen cannabis help with appetite loss, nausea and pain, but I have not observed it cure cancer in my 42 years of practice,” he said.
Abrams noted pre‑clinical data from test‑tube and animal studies are compelling, yet he stresses that human trials have not yet confirmed clinical benefit.
Implications for research and policy
Castle argues that the robust evidence meets or exceeds the standards for adopting new cancer therapies and urges the DEA to reclassify cannabis from a Schedule I substance to unlock further clinical research.
He cautioned that larger, controlled human trials are still required to define optimal formulations and dosing.
