Prostate cancer patients who smoke may be more susceptible to complications from their treatment, and at increased risk of side effects and disease recurrence, A Cancer Network report says according to a new study, patients who were current smokers had a 40% relative increase of cancer relapse and were twice as susceptible to disease spread and death due to prostate cancer compared with their non-smoking counterparts.
"Less optimal tumour control outcomes among smokers could possibly be explained by the influence of less oxygen concentration within the treated tumors among smokers, which is known to lead to less sensitivity of the cells being killed off by radiation treatments," said study author Dr Michael Zelefsky, of the Memorial Sloan Kettering Cancer Centre. "Our findings point to the importance of physicians counselling their patients regarding the potential harms of smoking interfering with the efficacy of therapies and for increased risks of side effects."
Prior studies have provided evidence of a link between smoking and both incidence of prostate cancer and death from prostate cancer. While the incidence studies range in outcomes, the link between smoking and an increased mortality are more consistent. The current study aimed to confirm this link and investigate whether smoking resulted in worse toxicity from external beam radiation therapy (EBRT) for these patients.
Zelefsky and colleagues analysed retrospective data from 2,358 patients who were treated with EBRT between 1988 and 2005; 49% of these patients were former smokers, 7.6% were current smokers, and 41% were never-smokers.
After undergoing EBRT, patients who were current smokers had a higher chance of side effects such as ¬ urinary retention, urinary incontinence, and bladder hemorrhage compared with those who had no history of smoking.
Current smokers had a 40% increased risk of prostate-specific antigen (PSA) relapse compared with non-smokers (P = .03), while former smokers had a similar risk of PSA relapse compared with never-smokers. The authors also found that current smokers had a higher risk of distant metastases after EBRT. The 10-year likelihood of distant metastases-free survival was 72.2% for current smokers, 85.8% for former smokers, and 87.3% for never-smokers (P < .001). Both current and former smokers had a greater risk of grade 2 and higher late onset genitourinary adverse events. Ten-year likelihood of high grade genitourinary toxicities were 14.6% for current smokers, 12.8% for former smokers, and 8.7% for never-smokers (P = .016).
According to the study authors, this study is one of the first large cohort studies of patients treated with radiotherapy for prostate cancer to show that "smoking can adversely influence survival outcomes and increase the risk of treatment-related toxicity."
[link url="http://www.cancernetwork.com/prostate-cancer/smokers-have-worse-prostate-cancer-outcomes"]Full Cancer Network report[/link]
[link url="http://onlinelibrary.wiley.com/doi/10.1111/bju.12969/abstract;jsessionid=5BE018FCEFA1EF3764E41B17AA304844.f03t02"]BJU International abstract[/link]