Among 1,472 bladder cancer patients, marijuana use (24.7%) was not associated with cancer recurrence or progression, while tobacco smoking duration and pack-years significantly increased recurrence risk.
Bladder cancer patients who use marijuana, urologists, and cancer survivorship researchers.
Marijuana: no recurrence link. Tobacco 40+ years: 2.4x recurrence risk.
What the researchers found
Longer cigarette smoking duration and more pack-years were associated with higher recurrence risk in a dose-dependent manner (40+ years: HR 2.36; 40+ pack-years: HR 1.97). No associations were found for marijuana, e-cigarettes, pipes, or cigars with bladder cancer recurrence or progression.
Why it matters
With nearly a quarter of bladder cancer patients reporting marijuana use, the absence of a recurrence association is reassuring for patients and clinicians, especially in contrast to the strong tobacco-recurrence link.
The numbers in context
1,472 patients. 363 (24.7%) used marijuana. 59.4% former smokers. 7.5% current smokers. Marijuana: no association with recurrence or progression. Tobacco 40+ years: HR 2.36 (95% CI 1.43-3.91). 40+ pack-years: HR 1.97 (95% CI 1.32-2.95).
How the study worked
Prospective Be-Well Study of 1,472 patients with non-muscle-invasive bladder cancer (NMIBC) diagnosed 2015-2019 in Kaiser Permanente California. Baseline interviews on tobacco, e-cigarette, and marijuana use. Cox regression estimated hazard ratios for recurrence and progression.
What this study cannot tell us
Self-reported substance use at a single time point. Marijuana use details (frequency, amount, duration) not fully captured. Relatively short follow-up (26.4 months). NMIBC-specific findings may not apply to other cancers.
How to read the evidence
Large prospective cohort in an integrated healthcare system with clinical outcomes, published in JAMA Network Open.
When this study was published
Published in 2022, patients diagnosed 2015-2019.
The bigger picture
This adds to the growing evidence that marijuana and tobacco have distinctly different cancer risk profiles, consistent with reviews suggesting marijuana does not appear to cause lung cancer either.
Questions still open
- Would longer follow-up reveal marijuana associations? Does the route of marijuana administration (smoking vs. edibles) matter for cancer outcomes?
Common questions
Does marijuana affect bladder cancer outcomes?
Is marijuana safer than tobacco for cancer patients?
Read the original research
Smoking Behaviors and Prognosis in Patients With Non-Muscle-Invasive Bladder Cancer in the Be-Well Study.
JAMA network open, 5(11), e2244430
Citation
Kwan, Marilyn L; Haque, Reina; Young-Wolff, Kelly C; Lee, Valerie S; Roh, Janise M; Ergas, Isaac J; Wang, Zinian; Cannavale, Kimberly L; Ambrosone, Christine B; Loo, Ronald K; Aaronson, David S; Quesenberry, Charles P; Kushi, Lawrence H; Tang, Li. (2022). Smoking Behaviors and Prognosis in Patients With Non-Muscle-Invasive Bladder Cancer in the Be-Well Study.. JAMA network open, 5(11), e2244430. https://doi.org/10.1001/jamanetworkopen.2022.44430
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