Medical marijuana policies, opioid prescriptions, and adverse events among patients undergoing cancer resection surgery.

BACKGROUND

Opioid use and adverse events among cancer patients may change with access to medical marijuana. This study investigated the impacts of medical marijuana legalization (MML) since 2016.

METHODS

Using a difference-in-differences approach and 2016 to 2022 private insurance claims data, this cross-sectional study included patients (aged 18-64 years) undergoing resection surgery for newly diagnosed (female) breast, colorectal, or lung cancer in 27 states without MML as of 2016. MML policies were classified into (1) no MML, (2) MML without dispensaries (after MML effective date and before the first state-licensed dispensary opened), and (3) MML with dispensaries. Outcomes included during the 6 months postdiagnosis: (1) any opioid prescription, (2) any short-acting oxycodone, hydrocodone, hydromorphone, or morphine prescription ("strong opioids"), (3) any short-acting tramadol or codeine prescription ("weak opioids"), and (4) total morphine milligram equivalents among patients with opioid prescriptions, (5) any all-cause, and (6) any pain-related emergency department visits or hospitalizations.

RESULTS

The sample (N = 34,911) included 24,592 patients with breast, 8510 colorectal, and 1809 lung cancer. Compared to no MML, MML with dispensaries was associated with reduced any strong short-acting opioids prescription use (difference = -4.6; 95% CI, -8.6 to -0.5 percentage points [pp]; p = .028) and increased any all-cause adverse hospital events (difference = 2.6; 95% CI, 0.7-4.5 pp; p = .006). MML without dispensaries was associated with increased any weak opioid prescription use (difference = 1.2; 95% CI, 0.5-2 pp; p = .002).

CONCLUSIONS

MML policies may have affected the type of opioid prescribed and increased adverse hospital events among patients with cancer and resection surgery. Additional investigation of medical marijuana's impact on cancer pain management is warranted.