3D-conformal hypofractionated radiotherapy for prostate cancer with daily transabdominal ultrasonography prostate localization: toxicity and outcome of a pilot study.

Aims And Background: To evaluate the feasibility, toxicity and patient outcome of hypofractionated 3-dimensional conformal radiotherapy for low- and intermediate-risk prostate cancer, using daily an ultrasound targeting system (BAT).

Methods: Between May 2005 and October 2006, 25 patients (cT1-T2, GS < or = 7, mean initial PSA = 7.06 ng/ml) received a dose of 72 Gy in 30 fractions. Only the prostate was included in the clinical target volume. Immediately before each radiotherapy session, BATTM ultrasound alignment was performed. Acute and late toxicity was evaluated according to the Radiation Therapy Oncology Group criteria; the Phoenix definition (PSA = nadir + 2 ng/ml) was applied to define biochemical failure. BAT localization data were provided for 300 out of 750 procedures.

Results: No interruptions in 3-dimensional conformal radiotherapy due to toxicity were registered. There was no acute rectal toxicity in 52% of patients; 28% had G1, 16% had G2, and 1 patient had a G3 event. No acute urinary toxicity was observed in 28% of the patients. G1 toxicity occurred in 40%, G2 in 28%, and G3 in 1 patient; no G4 event was observed. With an average follow-up of 45 months, one biochemical relapse was observed; late toxicity showed an excellent profile: 78% of the patients had no rectal toxicity, 16% had G1, and 1 patient had G2 toxicity. Most of the patients (68%) had no late urinary complications, whereas 32% had G1 toxicity. Localization data showed systematic and random errors in relation to some procedure biases.

Conclusions: Promising tumor control and toxicity profile were observed with this mildly hypofractionated BAT-based 3-dimensional conformal radiotherapy.