Phenobarbital use and bladder cancer risk.
BACKGROUND
Two epidemiologic studies have reported an inverse association between use of phenobarbital (PB) and bladder cancer development. It was proposed that PB use protects against bladder cancer by inducing enzymes that participate in the detoxification of human bladder carcinogens, such as the aminobiphenyls and naphthylamines, which are found in cigarette smoke.


METHODS
A population-based case-control study was conducted in Los Angeles, California, involving 815 incident bladder cancer cases and an equal number of controls who were matched to the index cases by neighborhood, sex, date of birth (within 5 years), and race. Detailed information on lifetime use of PB was collected through in-person interviews.


RESULTS
Ever use (20 or more times over lifetime) of PB was not associated with risk of bladder cancer (OR: 0.86; 95% CI: 0.54, 1.39). Regular use of PB also was not associated with risk of bladder cancer in either men or women, in either smokers or non-smokers, although the number of regular users in cases and controls were relatively small (21 cases vs. 15 controls, OR: 1.20; 95% CI: 0.59, 2.45). In fact, compared with non-users, subjects in the highest category of lifetime PB consumption were at a non-significant 2.46-fold increased risk of bladder cancer (95% CI: 0.90, 6.78).


CONCLUSIONS
The present study did not observe a protective role of PB use in bladder cancer development in the general population.
Castelao
J E
JE
Department of Preventive Medicine, USC/Norris Comprehensive Cancer Center, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089-9175, USA. castelao@hsc.usc.edu
Gago-Dominguez
M
M
Yuan
J M
JM
Ross
R K
RK
Yu
M C
MC
D017677:Age Distribution; D015982:Bias; D016022:Case-Control Studies; D004363:Drug Utilization; D015340:Epidemiologic Research Design; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000627:therapeutic use*; D015141:Los Angeles / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010634:Phenobarbital / Q000627:therapeutic use*; D012307:Risk Factors; D018426:SEER Program; D012907:Smoking / Q000009:adverse effects; D011795:Surveys and Questionnaires; D013997:Time Factors; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control*
D006993:Hypnotics and Sedatives; D010634:Phenobarbital