Role of CBD Oil in Malignancy Management
CBD oil should not be recommended for cancer treatment due to lack of evidence-based data supporting its anticancer effects, and it should be used with caution in patients receiving immunotherapy due to potential interference with treatment efficacy. 1
Evidence-Based Indications for CBD Oil in Cancer
Symptom Management
- CBD oil has no proven benefit for overall symptom burden in advanced cancer patients, as demonstrated in a recent phase IIb randomized controlled trial where CBD oil did not improve Edmonton Symptom Assessment Scale (ESAS) total symptom distress scores compared to placebo 2
- For chemotherapy-induced nausea and vomiting (CINV):
- CBD combined with THC (1:1 ratio) may be considered as a third or fourth-line option for refractory nausea and vomiting in patients receiving moderately or highly emetogenic chemotherapy who have failed guideline-concordant antiemetic prophylaxis 1
- This recommendation has a weak strength with low quality evidence for THC:CBD extracts 1
Dosing Considerations
- Do not exceed 300 mg per day of oral CBD due to risk of reversible liver enzyme abnormalities 1, 3
- When using cannabis extracts with 1:1 THC:CBD ratio, follow a dose of 1-4 self-titrated capsules of oral THC 2.5 mg:CBD 2.5 mg three times daily for refractory nausea/vomiting 3
- Follow a "start low, go slow" approach to minimize adverse effects 3
- Allow sufficient time between dose increases (30 minutes to 2 hours for oral preparations) to properly assess effects 3
Cautions and Contraindications
Immunotherapy Concerns
- Use CBD with extreme caution in patients receiving immunotherapy 1
- Cannabis consumption has been associated with:
- THC directly reduces the therapeutic effect of PD-1 blockade through suppression of T-cell antitumor immunity 1
Adverse Effects
- Common adverse effects include:
- Drug interactions are a significant concern, particularly with medications metabolized by CYP3A4, CYP2C9, and CYP2C19 3, 4
- High-risk drug interactions include warfarin, buprenorphine, and tacrolimus 3
Quality of Life and Other Outcomes
- No significant improvement in quality of life has been demonstrated in multiple studies:
- A 2022 systematic review of six RCTs found no clear evidence of benefit for quality of life in advanced cancer patients 1
- Another 2022 systematic review found a small, detrimental effect on QOL with THC-containing products 1
- A recent RCT of CBD oil versus placebo showed no significant difference in QOL as a secondary outcome 1
Anticancer Effects
- There is a lack of evidence-based data supporting CBD oil as an anticancer treatment 1
- While some preclinical studies suggest potential anticancer mechanisms 5, and there is a case report of tumor regression in a patient self-administering CBD oil 6, these findings have not been validated in clinical trials
- Clinicians should advise patients that using cannabis/cannabinoids as cancer-directed treatment may cause significant clinical and financial toxicities without good-quality evidence of clinical benefit 1
Clinical Approach
- When patients are using or considering CBD oil:
- For patients with refractory CINV, consider other options first, such as olanzapine (if not already used) or antiemetics from different classes (NK1 receptor antagonists, dopamine receptor antagonists, benzodiazepines) 1