"Not so. Obesity leads to worse cancer in both groups," study senior author Dr. Stephen Freedland, an associate professor of urology and pathology at the Duke University Medical Center Prostate Center, said in a news release from the school.
Freedland and study author Dr. Jayakrishnan Jayachandran, a urology oncology fellow, examined the medical records of 1,415 prostate cancer patients who had undergone a radical prostatectomy. They found that race had no influence on the relationship between obesity and the aggressiveness of the cancer.
"We found that higher BMI [body-mass index] was associated with significantly increased risk of cancer recurrence for both blacks and whites," Jayachandran said in the news release.
The reason why obesity increases the risk of prostate cancer recurrence isn't clear, but altered hormone levels might play a role.
"Obesity is associated with more estrogen and less testosterone, and it may be that lower testosterone promotes more aggressive tumors as recent studies have suggested," Jayachandran said.
Other obesity-related changes in the production of hormones, such as insulin, insulin-like growth factor or leptin, may also be involved in the development of more aggressive prostate cancer.
"This is something we simply do not understand, but we are actively studying all of these factors," Jayachandran said.
The study appears in the current issue of Cancer.
The American Cancer Society has more about prostate cancer.