Smoking Increases Risk of Relapse, Mortality, Treatment-Related Toxicity in Prostate Cancer

Smoking has an adverse effect on survival outcomes, such as biochemical relapse and mortality attributable to cancer, and radiotherapy-related adverse events in prostate cancer patients

medwireNews: Cigarette smoking during radiotherapy for prostate cancer elevates the risk of biochemical relapse, distant metastases, cancer-specific mortality and treatment-related genitourinary adverse events, research suggests.

“Given the increased risk of prostate cancer progression and radiation toxicity among smokers, a stronger emphasis on smoking cessation is clearly appropriate”, write Michael Zelefsky, from Memorial Sloan Kettering Cancer Center in New York, USA, and co-workers in BJU International.

The study included 2095 prostate cancer patients who had been treated with external beam radiotherapy (EBRT) at a median dose of 8100 Gy. Of these, 164 were current smokers (defined as individuals who were smoking when radiotherapy was initiated), 1054 were former smokers and 877 were never smokers.

Multivariate analysis showed that current smokers, but not former smokers, were significantly more likely to experience prostate-specific Antigen relapse compared with never smokers, at a hazard ratio (HR) of 1.40.

The risk of developing distant metastases and of prostate cancer-related death was also significantly higher in current than in never smokers, at HRs of 2.37 and 2.25, respectively. But the HRs for these outcomes did not differ significantly between the former and never smoker groups.

Additionally, being a current or former smoker was associated with a significantly increased risk of developing grade 2 or higher genitourinary toxicities following EBRT compared with never smokers, at HRs of 1.80 and 1.45, respectively.

“Whether a correlation exists between quantity of smoking exposure and an increased risk of prostate cancer mortality and biochemical recurrence is a matter of dispute”, say Michael Zelefsky et al. But they note that neither the quantity of smoking exposure, as assessed by pack–years, nor the duration had an effect on the studied survival outcomes or the risk of treatment-related toxicity in their “large retrospective” study.

They conclude: “Future studies will be required to validate these findings. In the meantime oncologists should encourage patients to participate in smoking-cessation programmes before therapy to potentially lower their risk of relapsing disease and post-treatment toxicities.”

Reference

Steinberger E, Kollmeier M, McBride S, et al. Cigarette smoking during external beam radiation therapy for prostate cancer is associated with an increased risk of prostate cancer-specific mortality and treatment-related toxicity. BJU Int; Advance online publication 27 January 2015. doi:10.1111/bju.12969

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