Ricchini F, Caraceni A, Zecca E, et al. - Via a secondary analysis of a placebo-controlled randomized trial comparing 100 μg fentanyl sublingual tablets (FST) with 5 mg subcutaneous morphine (SCM) for the acute treatment of severe cancer pain episodes, researchers examined how previous opioid exposure (oral morphine equivalent daily dose from 20 to 120 mg) impacts the analgesic effect of FST and SCM and whether it had an influence on their relative effect. In the 114 patients enrolled, only a modest and nonstatistically significant effect was seen by previous opioid exposure on all the outcomes examined. Outcomes suggest that previous opioid exposure, from 20 to 120 mg oral morphine equivalent daily dose, does not influence the absolute and relative efficacy and tolerability of 100 μg FST and 5 mg SCM for severe cancer pain episodes.