SAN DIEGO—Men with prostate cancer (PCa) treated with intensity modulated radiation therapy (IMRT) appear to have fewer gastrointestinal complications compared with patients who receive conventional three-dimensional conformal radiotherapy (3D-CRT), according to the largest study to date comparing complication rates between the two modalities.

“With survivors living many years after treatment, it is very important to minimize gastrointestinal and urinary side effects to allow patient to live a full life after treatment,” said lead investigator Justin Bekelman, MD, Assistant Professor of Radiation Oncology at the University of Pennsylvania in Philadelphia. “Our study shows there is a benefit for men with prostate cancer to receive IMRT over conventional treatment in terms gastrointestinal side effects.  But there is no difference between the two treatments in terms of urinary side effects.”

Using SEER (Surveillance, Epidemiology and End Results)-Medicare databases, Dr. Bekelman’s team studied 12,598 men aged 65 years and older who were diagnosed with non-metastatic PCa between 2002 and 2004. The researchers followed the patients through 2006 and identified complications that were serious enough to require invasive procedures (including surgeries) and/or hospitalization.

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Among men who received IMRT, 3.5% had serious complications related to rectal bleeding or proctitis during the two years post-treatment compared with 4.5% of men treated with 3D-CRT. “These numbers may sound small but they are quite significant, especially when you consider the fact that many thousands of men are treated with radiotherapy for prostate cancer ever year” said Dr. Bekelman, who presented study findings at the American Society for Radiation Oncology annual meeting.

With 3D-CRT, imaging studies, including computed tomography, magnetic resonance imaging, and positron emission tomography, are used to map the size, shape and location of tumors and the other organs in the area. IMRT is a more advanced version of 3D-CRT, offering a more targeted dose of radiation to the prostate gland.  Though Medicare and private insurers typically cover both IMRT and 3D-CRT, little research has been conducted to show which treatment is associated with fewer side effects, an important consideration for men choosing among the various treatment options for the disease.

This current study showed that IMRT was associated with a reduction in proctitis and rectal bleeding. Urinary complications, such as cystitis and hematuria, did not differ significantly between the groups. The researchers observed no substantial difference in the incidence of urinary or sexual side effects, such as erectile dysfunction, but Dr. Bekelman noted that the study was limited to complications involving invasive surgical procedures. He said this study may not have captured the true prevalence of sexual side effects following treatment, for which patients may have sought less invasive remedies.