Simultaneous Integrated Radiotherapy Boost to the Dominant Intraprostatic Lesion: Final Results of a Phase I/II Trial

Abstract

Background/aim: Late toxicity and long-term outcomes of a phase I-II trial on patients with prostate cancer treated with an integrated boost to the dominant intraprostatic lesion (DIL) are reported.

Patients and methods: Patients were treated using intensity-modulated radiotherapy, with a simultaneous integrated boost to the DIL, defined on staging magnetic resonance imaging, delivering 72 Gy in 1.8 Gy/fraction to prostate/seminal vesicles and 80 Gy in 2 Gy/fraction to the DIL. The primary endpoint was acute toxicity and secondary endpoints were late toxicity and biochemical disease-free survival.

Results: Forty-four patients were enrolled. The median follow-up was 120 (range=25-150) months. Five-year rates of grade 3 late gastrointestinal and genitourinary toxicity were 2.3% and 4.5%, respectively; only one grade 4 late genitourinary toxicity was recorded. Five-year biochemical relapse-free and overall survival rates were 95.3% and 95.5%, respectively.

Conclusion: The treatment was well tolerated and achieved excellent results in terms of outcome in patients with low-intermediate Gleason's score and low risk of nodal metastasis.

Keywords: Prostate neoplasms; dominant intraprostatic lesion; intensity-modulated radiotherapy; phase I-II; simultaneous integrated boost.