Smoking as a risk factor for prostate cancer: a meta-analysis of 24 prospective cohort studies.
OBJECTIVE
We evaluated the relationship between smoking and adenocarcinoma of the prostate.


METHODS
We pooled data from 24 cohort studies enrolling 21 579 prostate cancer case participants for a general variance-based meta-analysis. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated separately for mortality and incidence studies. We tested the robustness of effect measures and evaluated statistical heterogeneity with sensitivity analyses.


RESULTS
In the pooled data, current smokers had no increased risk of incident prostate cancer (RR = 1.04; 95% CI = 0.87, 1.24), but in data stratified by amount smoked they had statistically significant elevated risk (cigarettes per day or years: RR = 1.22; 95% CI = 1.01, 1.46; pack years of smoking: RR = 1.11; 95% CI = 1.01, 1.22). Former smokers had an increased risk (RR = 1.09; 95% CI = 1.02, 1.16). Current smokers had an increased risk of fatal prostate cancer (RR = 1.14; 95% CI = 1.06, 1.19). The heaviest smokers had a 24% to 30% greater risk of death from prostate cancer than did nonsmokers.


CONCLUSIONS
Observational cohort studies show an association of smoking with prostate cancer incidence and mortality. Ill-defined exposure categories in many cohort studies suggest that pooled data underestimate risk.
Huncharek
Michael
M
Meta-Analysis Research Group, Columbia, SC 29209, USA.
Haddock
K Sue
KS
Reid
Rodney
R
Kupelnick
Bruce
B
D000230:Adenocarcinoma / Q000209:etiology* / Q000401:mortality; D016009:Chi-Square Distribution; D016001:Confidence Intervals; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000209:etiology* / Q000401:mortality; D012306:Risk; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D016540:Smoking Cessation