06/21/2011 04:04 pm ET Updated Aug 21, 2011

Smoking And Prostate Cancer Death Linked: Study

A sweeping new study found that men with prostate cancer who smoked significantly increased their risk of dying, not just from the cancer itself, but also from cardiovascular disease.

The report adds to a mounting body of evidence that links fatal prostate cancer and cigarette use.

Writing in the Journal of the American Medical Association, researchers from Harvard University analyzed data from more than 5,000 men diagnosed with prostate cancer between 1986 and 2006.

They found that men who smoked at the time of their prostate cancer diagnosis had a twofold increased risk for overall mortality. The smokers also had a 61 percent increased risk that their prostate cancer would return.

"The last review by the U.S. Surgeon General found the evidence 'probable' that smoking contributes to a higher prostate cancer mortality rate," said Stacey Kenfield, a research associate with the Harvard School of Public Health and the study's lead author. "I think there is sufficient evidence available to more conclusively state that smoking is related to prostate cancer progression."

Kenfield said that the correlation could be because the nicotine in cigarettes induces the formation of new blood vessels and capillary growth, as well as tumor growth and proliferation, although the study did not analyze the causes behind the association.

The study -- which its authors say is the largest of its kind to date -- did have some good news for men who have kicked their nicotine habit.

The researchers found that men who had been smoke-free for at least 10 years had the same odds of dying from prostate cancer (and of prostate cancer recurrence) as men who had never smoked at all. Those who had quit smoking for less than 10 years at the time of their diagnosis and smoked 20 or more pack-years -- which is 365 packs of cigarettes -- had risks similar to active smokers in the study.

"In summary, smoking at the time of diagnosis was associated with substantially increased overall mortality and prostate cancer mortality and recurrence," the authors wrote. "These results provide further support that smoking may increase risk of death from prostate cancer."