New research findings show men have fewer long-term gastrointestinal side effects with intensity-modulated radiation therapy (IMRT) than with three-dimensional conformal radiation therapy (3D CRT) for prostate cancer treatment, despite the higher doses of radiation used in the IMRT group. These and other data, including long-term genitourinary side effects, were presented today at the 48th Annual Meeting of the American Society for Therapeutic Radiology and Oncology in Philadelphia.
Long-term data comparing 3D CRT for prostate cancer versus the use of IMRT is only now beginning to mature. Few other academic treatment centers have as much experience with 3D CRT and IMRT as Fox Chase.
Both techniques allow precise targeting of the cancer with multiple X-ray beams, but IMRT allows physicians to modulate the radiation dose intensity with far smaller radiation beams. Thus, doses of radiation to the bladder and rectum can be limited. Reducing radiation exposure to healthy normal tissue and other vital organs helps prevent once common side effects such as urinary frequency and diarrhea.
In the study presented today, researchers analyzed data collected prospectively from 1,417 patients treated at Fox Chase. Of these, 928 men were treated with 3D CRT (median follow-up of 63.3 months) and 489 men with IMRT (median follow-up of 29.9 months). The IMRT patients received higher doses of radiation.
Patients were matched for PSA level (prostate specific antigen, measured by a blood test and used to determine if prostate cancer is present), T-stage (palpable size) and Gleason score (tumor aggressiveness determined by pathologic testing). The researchers evaluated gastrointestinal side effects such as short-term diarrhea and longer-term bowel dysfunction and genitourinary side effects such as urinary frequency, urgency and, rarely, painful or difficult urination or obstructive symptoms.