Cannabis Laws and Opioid Use Among Commercially Insured Patients With Cancer Diagnoses

Pain is a prevalent cancer-related symptom, but limited research investigates whether cannabis is an effective analgesic for cancer pain.

To examine the association of medical and recreational cannabis dispensary availability on prescription opioid dispensing among commercially insured patients with cancer.

This cross-sectional study used synthetic control to investigate the association of cannabis dispensary openings with pain medication dispensing among patients with cancer. Data were extracted from Optum's deidentified Clinformatics Data Mart database from January 1, 2007, to December 31, 2020. The study population included patients aged 18 to 64 years with a cancer diagnosis and at least 6 months of continuous enrollment. Associations were estimated by age, race and ethnicity, and sex. Data were analyzed between December 2024 and February 2025.

Exposures included indicators for whether a medical or recreational cannabis dispensary was open in each state-quarter.

The outcome measures for opioids prescriptions were (1) the rate of patients with a prescription per 10 000 patients, (2) the quarterly mean days' supply per prescription, and (3) the quarterly mean number of prescriptions per patient.

The study included a mean (SD) of 3.05 (0.86) million patients annually across the US (mean [SD] age, 43.7 [9.6] years; mean [SD] 59.0% [0.32%] female). Medical cannabis dispensary openings were associated with significant reductions in all opioid outcomes. The rate of patients with cancer with opioid prescriptions changed by -41.07 per 10 000 (95% CI, -54.78 to -27.36 per 10 000; P < .001), the quarterly mean days' supply by -2.54 days (95% CI, -3.16 to -1.92 days; P < .001), and the mean number of prescriptions per patient by -0.099 (95% CI, -0.121 to -0.077; P < .001). Recreational dispensary openings were also associated with reductions in opioid outcomes, though estimated treatment effects were smaller. The rate of prescriptions changed by -20.63 per 10 000 (95% CI, -35.35 to -5.91 per 10 000; P = .049), the mean daily supply by -1.09 days supplied per prescription (95% CI, -1.72 to -0.46 days; P = .04), and the mean number of prescriptions per patient by -0.097 (95% CI, -0.134 to -0.060; P = .01).

This study's findings indicate cannabis may be a substitute for opioids in the management of cancer-related pain. However, further research directly observing cannabis use is needed to evaluate the efficacy of cannabis as a treatment for cancer-related pain.