Retrospective cohort study of opioid use and overdose in patients with solid tumors in Ontario

Opioids are essential for symptom control, but few studies have evaluated the association between prescription opioids and opioid overdose in oncology. A population-based, retrospective cohort study in Ontario (Canada) included adult patients with a newly diagnosed solid cancer from 2013 to 2020. Patients were followed from diagnosis to first opioid overdose event, death, or end of 2024. Among 554,316 patients, 1591 (0.3%) had one or more nonfatal opioid overdoses, and 191 (0.03%) had a fatal overdose. In the first year after diagnosis, patients with stage III and IV cancers had substantially higher rates of any opioid overdose than those with stage I. After adjustment, any opioid prescription in the prior 30 days was associated with 71% higher combined nonfatal and fatal opioid overdose rate (HR 1.71; 95% CI 1.47-2.00), and approximately 3.5 times higher if prescribed high-dose opioids (≥ 50 mg morphine-equivalent daily dose; HR 3.47-4.05), increasing by 3% per month of receiving such high-dose therapy. The authors conclude that these findings suggest that opioids should be used at the lowest effective dose with close monitoring for opioid overdose.