Background: Opioid prescribing in oncology is increasingly scrutinized given public health concerns about chronic opioid use, misuse, and harms. We aimed to evaluate patient reported pain scores, mental health indicators, prior opioid use, and number of opioid prescribers as potential risk factors for chronic opioid use in a large Canadian province. Methods: This was a population-based cohort study using administrative health data of patients in Alberta, Canada, diagnosed between Jan 2016 and Jan 2017, and completed a prospective comprehensive symptom survey within +/- 60 days of diagnosis. Patients were divided into two groups: chronic opioid use (COU) (defined as continuous prescriptions for opioids for at least 90 days post diagnosis) and non-chronic opioid use (NCOU). Logistic regression models were used to evaluate factors associated with COU. Results: We included 694 patients. Most had breast (20%), colorectal (13%), and lung (33%) cancers. There were no differences in mean age (65 years) or gender (50% female) between the groups. In total, 32% had moderate to high pain scores at diagnosis. Of the 14% with COU, 79% were opioid naïve at diagnosis. Those in the COU group were more often diagnosed with advanced stage of disease (66% vs 40%), had lung cancer (47%), and were opioid tolerant at diagnosis (defined as > 90 days of continuous opioids within 1 year prior to their diagnosis) (21% vs 3%). In comparison, 64% of COU versus 27% of NCOU had moderate to severe pain scores at diagnosis (p < 0.001). COU had significantly higher anxiety and depression scores at diagnosis versus NCOU (p = 0.004). Among patients with COU, morphine equivalent daily doses increased from 27.3 (pre-diagnosis) to 65.1 (post-diagnosis). Irrespective of treatment type or stage, those who had moderate to high pain scores, were opioid tolerant at diagnosis, or had multiple prescribers were at greater risk for COU (see Table). Conclusions: Specific patient groups were at increased risk of COU and should be the focus of adaptive prescribing approaches to ensure that opioid use is appropriate.