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Barbiturates, smoking, and bladder cancer risk
L A Habel1, S A Bull, G D Friedman
1Division of Research, Kaiser Permanente Medical Care Program, Oakland, California 94611, USA. lah@dor.kaiser.org
Summary
Phenobarbital use may reduce bladder cancer risk, particularly in smokers. This suggests phenobarbital might help detoxify cigarette carcinogens, offering a potential protective effect.
Area of Science:
- Pharmacology
- Oncology
- Epidemiology
Background:
- Phenobarbital treatment has shown a potential negative association with bladder cancer risk.
- The proposed mechanism involves phenobarbital inducing drug-metabolizing enzymes that detoxify cigarette smoke carcinogens.
Purpose of the Study:
- To investigate the relationship between barbiturate use and bladder cancer risk.
- To explore the modifying effect of cigarette smoking on this association.
Main Methods:
- A large cohort study of Kaiser Permanente members.
- Utilized computerized pharmacy prescription and smoking data.
- Identified bladder cancers via linkage with cancer registries.
Main Results:
- Overall standardized incidence ratio for barbiturate use was 0.71 (95% CI, 0.51-0.99).
- Inverse association observed primarily among current (SIR 0.56) and former smokers (SIR 0.68).
- No significant association found in never smokers (SIR 1.04).
Conclusions:
- Barbiturate treatment shows an inverse association with bladder cancer risk, especially in current and former cigarette smokers.
- Findings support the hypothesis that phenobarbital induces enzymes that deactivate cigarette-derived bladder carcinogens.