A history of smoking is associated with an increased risk of metastatic disease in patients treated with radiotherapy (XRT) for prostate cancer (CaP), according to a report in the online version of the BJU International.
The work is published by Dr. Pantarotto and colleagues in Ottawa, Canada.
In this retrospective review, 434 patients were treated with 66Gy of definitive radiotherapy between 1990 and 1999. To be included, patients had a PSA level less than 100ng/ml and no clinical or radiographic evidence of lymph node or distant metastasis. A smoking history categorized patients as non-smokers, previous smokers (>6 months smoking history but not smokers at time of consultation) or current smokers. Biochemical failure was defined by ASTRO criteria. Data regarding time to biochemical failure, time to local failure, time to distant failure, overall survival and disease-specific survival were generated.
A smoking history was obtained in 416 of 434 patients (96%) and the lifetime prevalence of smoking was 71%. Current smokers constituted 17% and non-smokers 29% of the cohort. Median follow-up was 70 months and current smokers presented at a younger median age of 66.4 years, compared with 69.9 years for previous smokers and 70 years for non-smokers. Clinical T stage, Gleason score and initial PSA were not significantly different between the smoking categories.
Biochemical, local and distant failure occurred in 44.6%, 23.2%, and 15.5% of patients, respectively. While biochemical and local failure rates were similar among smoking groups, a higher proportion of current smokers had distant failure events. Disease-specific survival was not significantly different among the three smoking groups, whereas overall survival was worse for current smokers than non-smokers (46% vs. 26%). The cohort death rate was 34%, with 39% of those deaths due to CaP. In univariate analysis, both previous and current smoking was associated with higher distant failure rates. In multivariate analysis, previous and current smokers had a higher risk of distant failure, 2.90 and 5.24, respectively. Overall and CaP-specific survival were not significantly different among the three smoking groups.
Several mechanisms have been proposed regarding the impact of smoking on CaP patient outcomes to XRT. Smoking-induced hypoxia secondary to high serum carboxyhemoglobin levels that interfere with hemoglobin-oxygen dissociation is thought to significantly contribute. Smoking also likely affects cellular mechanisms that result in tumor progression.
Jason Pantarotto, Shawn Malone, Simone Dahrouge, Victor Gallant and Libni Eapen
BJU Int 2006; 99(3): 564-569
By Christopher P. Evans, MD