Obesity linked with higher prostate cancer risk

Men who are overweight are more likely than thinner men to be diagnosed with Prostate cancers that are less likely to be detected on screening and more likely to be aggressive, according to a report in the medical journal Urology.

“Obesity may actually be associated with an increased risk of developing Prostate cancer, but various features among obese men make it harder to detect the cancer,” Dr. Stephen J. Freedland from Johns Hopkins School of Medicine, Baltimore, explained to Reuters Health. “If you do find them, it’s probably the more aggressive cancers that you are finding.”

Freedland and colleagues evaluated the relationship between body mass index (BMI), a height-to-weight ratio used to estimate body fat, and Prostate cancer and various other factors using data from 787 consecutive men undergoing prostate biopsy at Palo Alto Veterans Affairs Medical Center, Palo Alto, California.

These body mass index (BMI) numbers are used world-wide, by the World Health Organization (WHO), and nationally by the Centers for Disease Control and Prevention (CDC) and National Institutes for Health (NIH), to track of the world-wide and U.S. epidemic of Obesity.

Overall, BMI did not appear to be associated with the odds of being diagnosed with Prostate cancer. However, the authors report, a higher BMI was significantly associated with an increased odds of being diagnosed with prostate cancer after factoring in prostate-specific antigen (PSA) levels, digital rectal examination findings, prostate size and race.

Men with a BMI above 35 (indicating obesity), faced a 2.4-fold higher risk of being diagnosed with prostate cancer, compared with normal-weight men, the report indicates.

Higher prostate volume in obese men was the greatest contributor to obscuring the association between BMI and Prostate cancer development, the researchers note.

Prostate cancer
Prostate cancer involves a malignant tumor growth within the prostate gland.

The cause of prostate cancer is unknown, although some studies have shown a relationship between high dietary fat intake and increased testosterone levels. When testosterone levels are lowered either by surgical removal of the testicles (castration, orchiectomy) or by medication, prostate cancer can regress. There is no known association with benign prostatic hyperplasia (BPH).

After considering the contribution of PSA level, examination findings, prostate volume and race, a higher BMI was also associated with a significantly increased odds of a high Gleason score, a measure of tumor aggressiveness, the investigators report.

Specifically, the odds of having a high Gleason score were more than doubled among men with a BMI of 30 to 35, and quadrupled among men with a BMI of 35 or higher.

Freedland advises doctors to “be hypervigilant in looking for Prostate cancer among obese men.”
He recommends that obese men undergo standard PSA testing yearly, and for doctors to keep in mind that “the level may be lower than you’d expect. You might want to use a lower cutpoint for recommending biopsies.”

Freedland added: “Prostate size may be more important than we realize, so the biopsy protocol might need to be modified to account for that.”

Whether or more intensive screening can reduce the increased risk of prostate cancer deaths was observed among obese men before and just after measurement of PSA levels became commonplace still needs to be established, he and his colleagues conclude.

SOURCE: Urology, July 2005.

Provided by ArmMed Media
Revision date: June 11, 2011
Last revised: by Andrew G. Epstein, M.D.