Men who are obese at the time of being diagnosed with prostate cancer are more likely to see the cancer recur and ultimately die from it, according to a new study.

The research, conducted by Seattle's Fred Hutchinson Cancer Research Center and the University of Washington School of Public Health and Community Medicine, included 752 men aged 40-64 who were newly diagnosed with prostate cancer.

In interviews, the men provided their height and weight one year before their diagnosis. Researchers calculated the men's body mass indexes based on the height and weight figures and later compared survival rates to the men's BMIs.

The risk of death and recurrence in obese men was seen regardless of the treatment the men received for the cancer and was the same for men with low- or high-grade cancer.

"I was very surprised by the findings," said study author Dr. Alan Kristal, of the Fred Hutchinson center, in a news release.

Overall, men who had been obese one year before prostate cancer diagnosis were 2.6 times more likely than men with a normal BMI to die of prostate cancer, according to the study, which appears in the journal Cancer. Obesity also tripled the odds that men diagnosed with regional prostate cancer or cancer that had not spread, would see the cancer spread over the course of the year.

If the findings are correct, it could be one more reason for men to reach and maintain a normal weight, but further study is needed, Kristal said.