Obesity Undermines Radiation Treatment For Prostate Cancer

Obese men do not benefit from radiation treatment for prostate cancer as much as men who are not obese, say researchers from the University of Texas M.D. Anderson Cancer Center, Houston. This could help doctors decide how aggressive certain people's treatment should be.

Prof. Sara Strom, lead author, said "Prostate cancer for most men is quiet. It's a cancer with a good outcome. Basically, what you would like in prostate cancer is to identify men who have more chances of having a bad outcome, so you can do something different with them. Obesity is something to take into consideration."

You can read about this report in the journal Cancer, August 1.

However, some experts have questioned the validity of the report for two reasons:

1. The study refers to treatment carried out between 1998-2001. New radiation technologies have changed since then.
2. The number of obese men is the study was small.

Several studies have indicated that obesity is a complicating factor in many different cancers and their treatment outcomes. Men who are obese and get prostate cancer are more likely to suffer from the more aggressive forms. Prostate cancer patients who are obese have a much higher probability of having to have either the whole prostate or parts of it surgically removed (prostatectomy).

This is the first study to specifically look at how obesity may affect prostate cancer progression after radiation treatment. Prof. Storm and team looked at the medical records of 873 men who had prostate cancer - they had only received external beam radiotherapy for their disease. 5% of the men were either moderately or severely obese while 18% were mildly obese.

The researchers found a clear correlation between prostate cancer progression and the patients' body mass index (BMI). The higher a patient's BMI, the higher the likelihood of metastasis or tumor recurrence. They also found that the 5% who were moderately to severely obese were 99% more likely to have high levels of prostate-specific antigen.

Storm said that they found that after taking all other important risk factor for a bad outcome into consideration, obesity remained a significant risk factor, not only of rising PSA levels, but also with cancer recurrence and metastasis. The researchers are not sure why this may be the case.

Abstract
Influence of obesity on biochemical and clinical failure after external-beam radiotherapy for localized prostate cancer

The research was funded by the National Cancer Institute (NCI); Grant Number: CA84964, CA90270, NIEHS ES07784

The research team:

Sara S. Strom, PhD
Department of Epidemiology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Ashish M. Kamat, MD
Department of Urology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Stephen K. Gruschkus, MPH
Department of Epidemiology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Yun Gu, PhD
Department of Epidemiology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Sijin Wen, MS
Department of Biomathematics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Min Rex Cheung, MD, PhD
Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Louis L. Pisters, MD
Department of Urology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Andrew K. Lee, MD
Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Charles J. Rosser, MD
Department of Urology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
Deborah A. Kuban, MD
Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas

Written by: Christian Nordqvist
Editor: Medical News Today