The relationship between palliative radiotherapy and opioid prescribing patterns among patients with metastatic cancer.

Abstract

While randomized trials have established that palliative radiotherapy, especially to bone, can improve qualitative measures of pain, its quantitative relationship to opioid prescribing patterns has remained underexplored. We aimed to identify the association of palliative radiotherapy on opioid prescriptions received among patients with metastatic cancer. The Virginia Commonwealth University Institutional Review Board approved retrospective analysis extracted prescription data from all adult patients with metastatic cancer who underwent outpatient palliative external beam radiation therapy at Virginia Commonwealth University Health System from 2008-2018. Institutional prescribing data were used to calculate the average opioid oral morphine milligram equivalent (MME) dose 30, 60 and 90 days both before and after radiotherapy. Univariate and bivariate ordinary least squares (OLS) regression models were used to estimate the relationship of MME changes with clinical, radiation-related, and demographic patient factors. A total of 182 patients met inclusion criteria. Overall, patients required higher opioid doses after radiotherapy, with mean MME 30, 60, and 90 days prior to radiotherapy of 24.6, 20.2, and 16.8 mg, respectively; which increased to 62.9, 77.7 and 82.4 mg post-radiation therapy (P<0.01). Multivariate OLS models predicting the change of MME 60 days pre- and post-radiation treatment showed that younger age and comorbid depression predicted increased MME after radiotherapy. Patients with metastatic cancer face a relatively high opioid burden, which increases over time, even among those who receive palliative radiation therapy. Patients who are younger and have comorbid depression may have a higher risk of increased opioid burden after radiotherapy.