Los Angeles — While, at the population level, obesity is associated with prostate cancer (PC) mortality, little information is available on how obesity affects long-term PC-specific outcomes after initial treatment, according to a study in the journal Prostate Cancer and Prostatic Diseases.1
A study team led by Cedars-Sinai Medical Center researchers with participation from VA researchers from Los Angeles, Durham, NC, and Augusta, GA, conducted a retrospective analysis of 4,268 radical prostatectomy patients within the Shared Equal Access Regional Cancer Hospital (SEARCH) database.
Examined were associations between body mass index (BMI) and PC-specific mortality (PCSM) as the primary outcome. Secondary outcomes included biochemical recurrence (BCR) and castration-resistant PC (CRPC). BMI was used as a continuous and categorical variable with normal defined as less than 25 kg/m2, overweight as 25–29.9 kg/m2 and obese as greater than 30 kg/m2.
With a median follow-up among all surviving men at 6.8 years, 1, 384 men developed BCR, 117 developed CRPC and 84 died from PC.
Initial results indicated that higher BMI was not associated with risk of PCSM, BCR and CRPC. When BMI was categorized, overweight, with a hazard ratio (HR) of 1.99, and obesity (HR 1.97) were significantly associated with PCSM but not with BCR or CRPC.
On multivariable analysis adjusting for both clinical and pathological features, results were little-changed, in that obesity and overweight were associated with higher risk of PCSM but not with BCR or CRPC, except that the association for overweight was no longer statistically significant.
“Overweight and obesity were associated with increased risk of PCSM after radical prostatectomy,” the study authors concluded. “If validated in larger studies with longer follow-up, obesity may be established as a potentially modifiable risk factor for PCSM.”
The study posited that the connection between BMI and higher PC death rates is because:
- Obese men might be less-aggressively screened, leading to delayed detection.
- PC can be more difficult to detect in obese men, including physical challenges in performing a digital rectal examination and lower PSA further contributing to delayed detection.
- Obese men may receive less-aggressive and less-effective treatment.
- Obese men are less likely to undergo radical prostatectomy (RP), which some studies have shown results in lower PC death rates, and obese men are more likely to have positive margins at surgery.
- Vidal AC, Howard LE, Sun SX, Cooperberg MR, Kane CJ, Aronson WJ, Terris MK, Amling CL, Freedland SJ. Obesity and prostate cancer-specific mortality after radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital (SEARCH) database. Prostate Cancer Prostatic Dis. 2016 Oct 4. doi: 10.1038/pcan.2016.47. [Epub ahead of print] PubMed PMID: 27698439.