Tobacco use and external beam radiation therapy for prostate cancer: Influence on biochemical control and late toxicity

Background: The objective of this study was to examine the effect of tobacco use on disease control and late gastrointestinal and genitourinary toxicity in men undergoing external beam radiotherapy (EBRT) for prostate cancer.

Methods: In total, 633 men with known tobacco history at consultation underwent definitive EBRT between 1988 and 2008. Tobacco use was defined as positive (current or prior) or negative (never). The median EBRT dose was 74 gray (Gy). In univariate analysis, tobacco use and other prognostic factors were compared with disease control and toxicity. Multivariable analysis included tobacco use and the covariates that were associated with outcome on univariate analysis (P < .1).

Results: The rate of 5-year freedom from biochemical failure (FFBF) was 76% for current smokers, 81% for prior smokers, and 87% for never smokers (P < .02). Risk group, the percentage of involved cores, and EBRT dose ≥74 Gy were associated with FFBF (all P < .01). On multivariable analysis, smoking was not associated with FFBF (P = .19). Factors that were associated with late grade ≥2 genitourinary toxicity on univariate analysis included positive tobacco history, intensity-modulated radiotherapy, and EBRT dose ≥74 Gy (all P < .05). Prior transurethral resection of the prostate (P < .01) and current smoking status (P = .06) were associated with grade ≥3 toxicity. On multivariable analysis, a positive tobacco history was associated with grade ≥2 toxicity (hazard ratio, 1.45; P < .02), and current smoking status was associated with grade ≥3 toxicity (hazard ratio, 3.02; P < .05). Tobacco use was not associated with late gastrointestinal toxicity.

Conclusions: In men who are receiving EBRT for prostate cancer, tobacco use may be associated with higher rates of late grade ≥2 toxicity, and current smokers may have higher rates of late grade ≥3 genitourinary toxicity.