| Journal | Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer |
| Study Type | Observational Study |
| Population | Human participants |
This comprehensive review addresses a critical gap in oncology practice where substance use patterns—from therapeutic cannabis to problematic alcohol use—significantly influence cancer treatment outcomes. Understanding these relationships is essential for optimizing supportive care strategies and treatment adherence in cancer patients.
This narrative review synthesized evidence from January 2010 to April 2025 examining how alcohol, tobacco, cannabis, and opioids affect cancer care outcomes including diagnosis timing, treatment adherence, toxicity, and survival. Heavy alcohol use and continued tobacco use demonstrated clear associations with delayed diagnosis, poorer adherence, increased toxicity, and inferior survival outcomes. Cannabis and opioid evidence was more heterogeneous and predominantly observational, with interpretation limited by varied exposure definitions and study methodologies. The review highlights the complex interplay between substance use patterns and cancer care across the treatment continuum.
“This review confirms what we observe clinically—substance use profoundly shapes cancer outcomes, but our understanding remains frustratingly incomplete for cannabis and opioids where patients need clearer guidance. The heterogeneity in cannabis research particularly underscores the urgent need for standardized exposure metrics in oncology studies.”
💬 Join the Conversation
Have a question about how this applies to your situation? Ask Dr. Caplan →
Want to discuss this topic with other patients and caregivers? Join the forum discussion →
Have thoughts on this? Share it:
FAQ
How does cannabis use affect cancer treatment outcomes compared to alcohol and tobacco?
Unlike alcohol and tobacco which show well-established negative impacts on cancer outcomes, the evidence for cannabis is heterogeneous and predominantly observational. Heavy alcohol use and continued tobacco use are consistently associated with delayed diagnosis, poorer treatment adherence, greater toxicity, and inferior survival. Cannabis effects remain unclear due to variability in study designs and exposure definitions.
Should I be concerned about my patient’s cannabis use during cancer treatment?
While the evidence is mixed, cannabis use warrants clinical attention as part of comprehensive substance use assessment in cancer patients. The study indicates that substance use across the spectrum can impact diagnostic timing, treatment adherence, toxicity profiles, and symptom burden. Regular monitoring and open discussion with patients about all substance use is recommended.
Does cannabis use affect chemotherapy adherence in cancer patients?
The study identifies treatment adherence as a key outcome affected by substance use, though specific evidence for cannabis impact on adherence appears limited and heterogeneous. Unlike alcohol and tobacco which show clear negative effects on adherence, cannabis effects on treatment compliance require further research. Clinicians should assess and monitor adherence patterns in cannabis-using patients.
Can cannabis use influence cancer diagnosis timing?
While heavy alcohol and tobacco use are associated with delayed cancer diagnosis, the evidence for cannabis impact on diagnostic timing is not well-established according to this review. The heterogeneous nature of cannabis research makes it difficult to draw definitive conclusions. However, any substance use should be considered when evaluating factors that might affect healthcare engagement and diagnostic processes.
How should oncologists approach substance use screening in their cancer patients?
Given that substance use spans a continuum and can shape outcomes across the cancer care continuum, comprehensive screening for alcohol, tobacco, cannabis, and opioids should be standard practice. The study emphasizes that substance use affects multiple domains including symptom burden, treatment toxicity, and survival outcomes. Regular assessment allows for appropriate supportive interventions and monitoring.
