Research study · Supportive Care in Cancer · 2025
Medicinal cannabis for symptom control in advanced cancer: a double-blind, placebo-controlled, randomised clinical trial of 1:1 tetrahydrocannabinol and cannabidiol
Verified on PubMed Oxford CEBM Level 1B: Randomized Controlled Trial
A 2025 randomized controlled trial in Supportive Care in Cancer tested medicinal cannabis in cancer. The cannabis oil made no difference to total symptom distress compared to the inactive oil, though it led to a small improvement in pain. An honest negative result on the headline question.
In plain language
Study overview
Researchers followed adults with advanced cancer receiving palliative care to see if a daily plant oil containing equal parts of active cannabis compounds could lower their overall distress. Participants took either the cannabis oil or an identical-looking inactive oil, starting with low amounts and adjusting upwards over four weeks while keeping their usual medical care.
Findings
The cannabis oil made no difference to total symptom distress compared to the inactive oil, though it led to a small improvement in pain. Patients taking the cannabis oil also experienced significantly more mental side effects, such as feeling high, confusion, and altered well-being.
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The deeper readScientific analysis
Patients with cancer commonly access cannabis hoping to relieve their symptoms. This study assessed whether a 1:1 10 mg/ml THC:CBD combination oil could improve total symptom burden in patients with advanced cancer over that provided by palliative care alone. Participants were randomised to medicinal cannabis (MC) or placebo oil; dose escalated over 14 days according to tolerance and efficacy and continued to day 28. Symptoms assessed using the Edmonton Symptom Assessment Scale (ESAS) were summated to give a total symptom distress score (TSDS). The primary outcome measure was the change from baseline in TSDS at day 14. Secondary outcomes included individual symptom scores, opioid use, participant-selected dose, QoL, psychological symptoms, global impression of change (GIC), and adverse effects. The pre-planned sample size of 120 at day 14 was reached following the randomisation of 144 patients. Mean (SD) TSDS improved over time in both arms (-6.30 (12.3) MC, -6.98 (12.56) placebo, p=0.76) to day 14 with no difference between arms. A statistically significant improvement in ESAS pain scores in the MC arm (mean (SD) -1.42 (2.15) MC and -0.46 (2.83) placebo, p=0.04) was at the expense of greater psychomimetic toxicity. Improvement in general well-being was greater for the placebo. GIC and the pain component of QoL both favoured MC. Patients can be informed that a 1:1 THC:CBD combination cannabis oil was no better than palliative care alone in palliating symptoms in patients with advanced cancer. A small benefit in pain control was associated with greater toxicity.
The paper
Citation
Hardy JR, Greer RM, Pelecanos AM, Huggett GE, Kearney AM, Gurgenci TH, et al. Medicinal cannabis for symptom control in advanced cancer: a double-blind, placebo-controlled, randomised clinical trial of 1:1 tetrahydrocannabinol and cannabidiol. Supportive Care in Cancer (2025). PubMed 40705150 · DOI
Limitations the authors noted
High attrition rate characteristic of advanced cancer palliative care trials (54.2% exited before day 28 in active arm, 30.5% in placebo). Imbalance in baseline opioid use between study arms (85.9% on active vs 68.1% on placebo). Most participants recruited from a single primary clinical centre. Study was not specifically powered for secondary outcomes like individual pain scores.
In practice
Why this matters
An honest negative result on the headline question. It is a useful corrective: people often arrive hoping cannabis will lift everything at once, and this trial says that is not what happened.
Frequently asked questions
Clinical Questions & Answers
What did this study show regarding CBD for Cancer?
Overall symptom distress improved in both groups by a similar amount, with no difference between them. Pain scores improved more on cannabis, but with more psychological side effects, and general wellbeing favoured placebo.
How does Dr. Benjamin Caplan interpret these results for clinical practice?
An honest negative result on the headline question. It is a useful corrective: people often arrive hoping cannabis will lift everything at once, and this trial says that is not what happened.
Who participated in this trial and what methodology was used?
A placebo-controlled trial asking whether a 1:1 THC:CBD oil eased the overall symptom burden of advanced cancer beyond what palliative care already provides.
Browse related research
Condition: Cancer Topic: CBD Topic: Medical cannabis Topic: THC
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Reviewed by Dr. Caplan on September 17, 2026.
This page is general education about a published study. It is not medical advice and does not create a doctor-patient relationship. For care specific to you, book a consultation.