Smoking may increase risk of death from prostate cancer

Men who are diagnosed with prostate cancer and who are also smokers have an associated increased risk of all-cause, cardiovascular and prostate cancer-specific death, according to a study in the June 22/29 issue of JAMA. These patients also had an increased likelihood of prostate cancer recurrence.

Accumulating evidence suggests that smoking may increase risk of aggressive prostate cancer and prostate cancer mortality. However, studies of smoking in relation to prostate cancer mortality or recurrence in prostate cancer patients are limited, with few prostate cancer-specific outcomes, according to background information in the article.

Stacey A. Kenfield, Sc.D., of the Harvard School of Public Health, Boston, and colleagues conducted a study to assess the relation of cigarette smoking and smoking cessation with overall, prostate cancer-specific, and cardiovascular disease (CVD) mortality and biochemical recurrence among men with prostate cancer. The study included 5,366 men diagnosed with prostate cancer between 1986 and 2006 in the Health Professionals Follow-Up Study.

Among the men diagnosed with prostate cancer, there were 1,630 deaths, 524 (32 percent) due to prostate cancer and 416 (26 percent) to CVD, and 878 biochemical recurrences. Analysis indicated that compared with never smokers, current smokers had an increased risk of dying from prostate cancer, CVD, and all-cause mortality and an increased risk of biochemical recurrence. A greater number of pack-years was associated with an increased risk of prostate cancer mortality, CVD mortality, and total mortality but not biochemical recurrence. Compared with current smokers, men who had quit smoking for 10 or more years had prostate cancer mortality risks similar to those who had never smoked.

The authors write that a direct effect of smoking on prostate cancer progression is biologically plausible, including tumor promotion through carcinogens from tobacco smoke; increased plasma levels of total and free testosterone, an androgen involved in the development and progression of prostate cancer in some smokers, with some studies reporting a dose-dependent association; epigenetic effects, including aberrant methylation profiles among current smokers, which correlate with aggressive disease; and nicotine-induced angiogenesis [formation of new blood vessels], capillary growth, and tumor growth and proliferation.

"In summary, smoking at the time of diagnosis was associated with substantially increased overall mortality and prostate cancer mortality and recurrence. Ten-year quitters had risks similar to never smokers. These results provide further support that smoking may increase risk of death from prostate cancer," the authors conclude.