The finding stems from work involving more than 3,300 prostate cancer patients with an average age of 60 who underwent surgery between 2001 and 2007 to remove a malignant prostate gland and surrounding tissue.

"As the patient's body mass index [BMI] increased, the tumor volume increased synchronously," Dr. Nilesh Patil, from the department of radiology at the Henry Ford Hospital's Vattikuti Urology Institute in Detroit, said in a news release. "Based on our results, we believe having a larger percentage of tumor volume may be contributing to the aggressive nature of the disease in men with a higher BMI."

BMI is a measurement of body fat that takes into account a person's weight and height. In the study, BMI scores ranged from 24.9 or less for normal to underweight individuals, to 40 or higher for morbidly obese individuals, the team noted.

Patil's team is slated to present the findings Wednesday in San Francisco at the American Urology Association annual meeting.

The authors noted that prior research had already established that aggressive prostate cancer was linked to having a higher BMI.

To explore whether or not the cancer-BMI association translated into bigger tumor size, the research team weighed and compared tumors that had been removed from the patients.

The authors found that in every BMI category -- underweight, normal, overweight, obese and morbidly obese -- tumor size correlated directly with patient weight, with lower-weight patients having smaller tumors and higher-weight patients having larger tumors.