Medical Cannabis Laws Were Linked to Lower Opioid Dispensing Among Some Cancer Patients
A 2023 study published in JAMA Oncology found that state medical marijuana legalization was associated with lower opioid dispensing and fewer pain-related hospital events among some adults receiving treatment for newly diagnosed cancer. The findings suggest cannabis may have served as an alternative or supplement to opioid therapy for some patients—but the study did not establish that cannabis use directly caused the decline.
Researchers analyzed insurance-claims data from 38,189 people newly diagnosed with breast cancer, 12,816 with colorectal cancer and 7,190 with lung cancer. All participants were ages 18 to 64, privately insured and receiving anticancer treatment. The analysis compared outcomes in states that implemented medical marijuana laws between 2012 and 2017 with outcomes in states that had not yet done so.
After legalization, opioid dispensing declined in several patient groups. Among patients with a recent history of opioid prescriptions, the proportion receiving at least one opioid day fell from 90.1% to 84.4% for those with breast cancer and from 89.4% to 84.4% for those with colorectal cancer. Among lung cancer patients without recent opioid use, the rate fell from 33.8% to 27.2%. These changes represented relative reductions of approximately 5.5% to 19.2%.
The study also found fewer pain-related hospital events among lung cancer patients who had recently used opioids: the rate declined from 19.3% to 13.0% after medical marijuana legalization. However, the researchers could not determine whether patients were using cannabis, whether cannabis replaced opioids, or whether other changes in prescribing practices, access to care or state policy explained the results. The study was observational and based on claims data, so it cannot demonstrate cause and effect.
Cannabis and cannabinoid products are used by some patients to address pain, nausea, poor appetite, sleep problems and other symptoms associated with cancer or its treatment. The National Cancer Institute’s evidence review notes that the FDA has approved the cannabinoid medicines dronabinol and nabilone for chemotherapy-related nausea and vomiting that has not responded adequately to conventional treatment. Cannabis itself is not FDA-approved to treat cancer, and evidence for many other uses remains limited or mixed.
Medical cannabis also has potential risks, including sedation, impaired concentration, dizziness, cardiovascular effects and drug interactions. Concentrated cannabidiol products may affect enzymes involved in metabolizing some medications, including certain cancer treatments. Patients should therefore discuss cannabis use with their oncology team rather than replacing prescribed treatment or changing opioid therapy without medical supervision.
Opioids remain an important option for many people with moderate or severe cancer-related pain. The CDC’s opioid-prescribing guideline specifically excludes cancer-related pain, palliative care and end-of-life care because these situations involve different clinical goals and require individualized decisions. The JAMA Oncology study is best understood as evidence of an association between medical marijuana laws and prescribing patterns—not proof that cannabis is safer or more effective than opioids for every patient.
For clinicians, the findings underscore the need to ask patients about cannabis use and provide balanced information about possible benefits, limitations and interactions. Coordinated care among oncologists, pain specialists, palliative-care clinicians and other qualified providers can help patients manage symptoms while ensuring that cancer treatment and pain control remain appropriately supervised.
