Clinical Trial Finds Medical Cannabis Extracts Improve Cancer-Related Symptoms in About Half of Patients

A new randomized, placebo-controlled, triple-blind clinical trial found that medical cannabis extracts may provide meaningful relief for cancer-related symptoms in about half of patients, particularly for sleep, anxiety and daytime tiredness.

The study, posted as a medRxiv preprint and not yet peer reviewed, involved clinically stable but symptomatic outpatients from eight Canadian cancer centers. Participants tested three blinded sublingual cannabis extracts—THC-dominant, CBD-dominant and a balanced 1:1 THC:CBD extract—along with a placebo, using an aggregate n-of-1 trial design in which each participant served as their own control.

Researchers found that 50 of 89 participants, or 56%, experienced at least a 1.4-point improvement on a 7-point Patient Global Impression of Change scale with at least one cannabis extract compared with placebo. Response rates were 50% among those whose primary symptom was pain, 47% among those with sleep disturbance and 60% among those with anxiety.

All three active extracts were significantly more effective than placebo on average, but no single extract was clearly superior overall. Instead, researchers said most participants had a stronger response to one extract over the others, suggesting that treatment may need to be personalized.

The study found that improvements in sleep, anxiety and tiredness contributed most to the overall benefits, regardless of a participant’s primary symptom. Researchers also reported that mild adverse effects were common across all extracts, including placebo, but generally resolved quickly after lowering or stopping the dose. Moderate or severe adverse effects were rare, though they were more often associated with THC.

The authors concluded that medical cannabis extracts “can be meaningfully beneficial for cancer-related symptoms in approximately 50% of patients,” while emphasizing the need for individualized treatment approaches.