Longitudinal assessment of benefits and harms of cannabis use among community-based cancer patients during initial cancer treatment

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Despite federal prohibition on the sale or prescribing of cannabis and cannabinoids (CAC), their medical use has been legalized in 37 states. Although there is limited evidence of its effectiveness, 18-42% of persons with cancer report using CAC to help manage symptoms, most of whom obtain advice from local CAC dispensaries rather than their oncology providers. Almost 50% of oncologists recommend CAC for their patients, but <30% feel sufficiently informed to make specific recommendations. Thus, there is an urgent need for more research to guide both patients and providers on the optimal use of CAC in oncology care. There is strong evidence on the benefits of CAC for the treatment of chemotherapy-induced nausea and vomiting and for mitigating general chronic pain. There is weaker evidence on the effectiveness of CAC to help manage other symptoms that many persons with cancer report using it for, including appetite loss, depression, anxiety, and insomnia. No studies have been done on whether CAC use by cancer patients changes their use of standard palliative therapies, such as opioids to manage pain, and the mechanism by which this occurs. Well-known negative effects of CAC use have not been well studied, and may include an increased risk of infections, injuries, reduced memory and concentration, cannabis use disorder, and increased use of tobacco and alcohol. In response to these knowledge gaps, we propose a longitudinal observational study in a community-based health care setting comparing CAC users to non-users on the safety and effectiveness of CAC. We will enroll persons with incident colorectal or non-small cell lung cancer, or with non-Hodgkin Lymphoma, who are initiating systemic primary or adjuvant cancer therapy. We anticipate that 25% of the study cohort will report using CAC based on prior surveys and our preliminary data. We will survey persons soon after therapy is started, and conduct follow-up surveys 2, 4, 6, and 12 months later. We will use validated survey instruments to collect CAC use, and use PROMISÒ measures to capture patient reported outcomes (PROs). To obtain more granular details on CAC use for symptom control, we will also conduct brief (5 minute), weekly, daily assessments in a subset (n=500) of subjects, including all CAC users. We will conduct our study within the Kaiser Permanente Southern California health plan to capitalize on the availability of a high volume of eligible cases and comprehensive electronic health records containing essential clinical data. Our specific aims are to: 1. Assess the effects of CAC use on PROs, focusing on pain, nausea, anxiety, depression, insomnia, appetite loss, and overall HRQOL (defined by physical, emotional, social functioning) among persons undergoing active systemic cancer therapy; 2. Assess whether and how CAC use affects the use of standard palliative therapies, such as reducing the use of opioids; and 3. Assess the negative effects from CAC use. The rapid increase in CAC use by cancer patients has occurred despite the lack of evidence about its effectiveness and safety. Our study will inform the best clinical strategies and policies for limiting potential harms and enhancing benefits.