Previous studies have examined the connection between prostate cancer and smoking, and it is clear that the two are linked. However, researchers at Memorial Sloan Kettering wanted to further investigate how smoking affects the progression of prostate cancer and treatment for prostate cancer, specifically external beam radiotherapy (also known as radiation).
The study involved 2,358 prostate cancer patients who were treated with radiation between 1988 and 2005. Of the 2,358 patients, 2,156 had a history of smoking. The study categorized the patients into four categories: never smokers, former smokers, current smokers, and current smoking unknown. Nearly 50 percent of participants were former smokers, and included those who had only quit shortly before treatment.
Researchers followed the patients for about eight years, monitoring radiation side effects, disease progression, recurrence, symptoms, and deaths. They found that patients who were current smokers had a 40 percent increased risk of prostate cancer recurrence, and more than two-times increased risk of metastasis and death, compared to patients who were never smokers. Former smokers and current smokers had a higher risk for negative side effects from radiation, such as urinary incontinence, urinary retention, and bladder hemorrhage, compared to those who never smoked.
They also found that those who never smoked were 66 percent likely to survive ten years without experiencing a recurrence of prostate cancer, compared to former smokers who were 62 percent likely and current smokers who were 52 percent likely to survive ten years without experiencing a recurrence.
Dr. Zelefsky, the study’s co-author and the vice chair of clinical research in the department of radiation oncology at Memorial Sloan Kettering, states that the purpose of this study was not to show how smoking worsens prostate cancer, but to investigate a possible hypothesis that smoking may reduce oxygen concentration in the tumor, making radiation less effective in shrinking the tumor.
“So, at minimum this should make us more cognizant of the need to get a good smoking history on prostate cancer patients, and to get more proactive in terms of referring them for smoking cessation programs, rather than putting the issue on the backburner while undergoing treatment,” Dr. Zelefsky said.