Three-dimensional conformal radiotherapy in localized carcinoma of prostate: preliminary reports of toxicity in dose-escalation treatment

PURPOSE. Many studies confirmed the evidence of a dose-response relationship
in prostate cancer. Escalation of dose using conventional techniques is however limited by
rectal tolerance. IMRT and 3D-CRT have been designed to allow dose escalation while not
exceeding rectal tolerance. We evaluated the acute and early late tolerance to surrounding
organs upon dose escalation from 70 to 78 Gy in 3D-CRT setting, in order to introduce the
IMRT process as a routine practice in prostate cancer treatment.
MATERIALS AND METHODS. We compared clinical data from 35 patients with localized adenocarcinoma
of the prostate, who received 70 Gy within a traditional reconstructed three-dimensional
treatment planning, and data from 72 patients who received 78 Gy within a threedimensional
conformal setting.
In order to respect rectal tolerance in the higher dose group, limits were set for rectum doses,
and simulation procedures were standardized. We evaluated radiation morbidity (acute
and late gastrointestinal and genitourinary toxicity) using the Radiation Therapy Oncology
Group scoring criteria (RTOG scale).
RESULTS. Increasing doses from 70 Gy to 78 Gy resulted in no significant difference for acute
and late effects.
CONCLUSION. A procedural standardization aiming at minimizing day-by-day variation, as well
as a more consistent dose distribution to critical organs may significantly reduce the risk
of increased toxicity in dose-escalation setting.