CHICAGO Smoking increases the risk that men who develop prostate cancer will die from their disease, U.S. researchers said on Tuesday.
The longer the men smoked, the greater the risk, said Stacey Kenfield of the Harvard School of Public Health in Boston, whose study appears in the Journal of the American Medical Association.
Kenfield and colleagues studied 5,366 men diagnosed with prostate cancer between 1986 and 2006.
"We compared current smokers to never smokers. Compared to never smokers, current smokers had a 61 percent increased risk of dying of prostate cancer, as well as a 61 percent increased risk of having their cancer return," Kenfield said in a telephone interview.
But men who quit smoking at least a decade before they developed cancer appeared to be able to avoid that increased risk.
The study coincides with the release of graphic new health warnings against cigarettes that must show up on packages and advertising next year, in a bid to convince more smokers to quit.
Compared with current smokers, men who had quit for 10 or more years had about the same risk of dying from their prostate cancer as those who had never smoked, Kenfield and colleagues found.
Prostate cancer is the second-leading cause of cancer death in men behind lung cancer.
According to the American Cancer Society, nearly 241,000 U.S. men will be diagnosed with prostate cancer in 2011, and nearly 34,000 men are expected to die from it.
BETTER TO QUIT
Men in the study who were smokers had more advanced disease when they were diagnosed with prostate cancer than non-smokers. This may be because smokers are less likely to get regular screenings, but it may also mean that smoking contributes to a more aggressive form of prostate cancer, Kenfield said.
But even when they controlled for the stage of disease, men who were smokers at the time they were diagnosed with prostate cancer were more likely to die from the disease, she said.
One potential reason is that smoking encourages angiogenesis -- the growth of tiny blood vessels -- which can fuel cancer growth by providing a source of blood to tumors.
Kenfield said the study was not big enough to see if quitting smoking at the time of diagnosis could slow growth of prostate tumors, but she said it might be a good idea anyway.
"Smoking is related to so many chronic diseases. One in six men get prostate cancer, but only one in 36 men die of it. Most men will die of something else," Kenfield said.
She said even if smoking does not cause men to die of prostate cancer, they could die of other smoking-related diseases.
Dr. Elizabeth Kavaler of Lenox Hill Hospital in New York, who was not involved in the study, said the findings make sense because smoking weakens the immune system and cancer-causing agents in tobacco can promote tumor growth and progression.
"It is interesting to see that smoking is an independent risk factor for progression, unrelated to heart disease and other known complications of smoking," Kavaler said in a statement.
(Editing by Cynthia Osterman)