One of the most conspicuous omissions in clinical oncology is the failure to generate accumulated empirical evidence about long-term opioid therapy in patients with persistent cancer or treatment-related pain. In response to the Centers for Disease Control and Prevention (CDC) opioid guideline for chronic pain,1 the American Society of Clinical Oncology (ASCO) noted that, despite the existence of multiple guidelines for pain management, evidence is lacking in many aspects of opioid use and studies on long-term opioid therapy in patients with cancer are sorely lacking.2 For instance, most trials that evaluate the outcomes of opioid therapy, such as pain, function, and quality of life, are 6 weeks or shorter and the CDC opioid guideline authors found no studies that investigated the effectiveness of opioid therapy long-term.1 This is despite the fact that long-term opioid therapy is prevalent among cancer survivors compared with age- and sex-matched controls, and, based on recent data, opioid therapy may continue for months to years after the initial diagnosis of cancer.3