Effect of cigarette smoking on biochemical outcome after permanent prostate brachytherapy

Abstract

Purpose Recent studies have suggested that cigarette smoking may be associated with an increased risk of death from prostate cancer. In this study, we evaluated the effect of cigarette smoking on the presentation and biochemical outcome after permanent prostate brachytherapy for prostate cancer. Methods and materials A total of 582 patients underwent brachytherapy with generous periprostatic margins using either 103Pd or 125I with or without supplemental external beam radiotherapy between April 1995 and September 2000. Of the 582 patients, 178 (30.6%) had never smoked, 306 (52.6%) were former smokers, and 98 (16.8%) were current smokers. The median patient age was 67.9 years, and the median follow-up was 54.5 months. No patient was lost to follow-up. No patient underwent routine seminal vesicle biopsy or pathologic lymph node staging. The clinical, treatment, and dosimetric parameters evaluated included tobacco status, age, clinical stage, Gleason score, pretreatment prostate-specific antigen level, risk group, percentage of positive biopsies, ultrasound volume, isotope used, planning volume, hormonal status, use of external beam radiotherapy, and postimplant dosimetry (percentage of target volume receiving 100%, 150%, and 200% of the prescribed dose and percentage of prescribed dose covering 90% of the target volume). Biochemical outcome was determined using the American Society for Therapeutic Radiology and Oncology consensus definition. Results No differences in the clinical, treatment, or dosimetric parameters were identified, except that current smokers were statistically younger than those who had never smoked or former smokers (65.9 vs. 67.8 vs. 68.3 years, respectively, p = 0.016). Specifically, no relationship was discerned between tobacco history and risk group, supplemental external beam radiotherapy, choice of isotope, or use of hormonal therapy. The overall biochemical freedom from progression survival rate at 7 years was 96.2%, 95.6%, and 91.6% for patients who had never smoked, former smokers, and current smokers, respectively ( p = 0.126). When stratified by risk group and hormonal status, tobacco consumption did not predict outcome, although a trend for poorer biochemical progression-free survival was noted in current smokers. The median prostate-specific antigen level for hormone-naive and hormonally manipulated disease-free patients was <0.1 ng/mL. In multivariate Cox regression analysis, Gleason score, pretreatment prostate-specific antigen level, risk group, and hormonal status were predictors of biochemical outcome. Conclusion In this prostate brachytherapy cohort, tobacco consumption did not predict for risk group stratification or treatment approach. Although no statistically significant difference was found in biochemical progression-free survival, a trend for poorer biochemical outcome was demonstrated in current smokers.