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Hypofractionated Boost to the Dominant Tumor Region With Intensity Modulated Stereotactic Radiotherapy for Prostate Cancer: A Sequential Dose Escalation Pilot Study

2009; Elsevier BV; Volume: 78; Issue: 1 Linguagem: Inglês

10.1016/j.ijrobp.2009.07.1689

1879-355X

Raymond Miralbell, Meritxell Mollà, M. Rouzaud, A. Hidalgo, José Ignacio Toscas, J. Lozano, Sergi Sanz, C. Ares, S. Jorcano, D. Linero, Lluís Escudé,

Advanced Radiotherapy Techniques

To evaluate the feasibility, tolerability, and preliminary outcomes in patients with prostate cancer treated according to a hypofractionated dose escalation protocol to boost the dominant tumor-bearing region of the prostate.After conventional fractionated external radiotherapy to 64 to 64.4 Gy, 50 patients with nonmetastatic prostate cancer were treated with an intensity-modulated radiotherapy hypofractionated boost under stereotactic conditions to a reduced prostate volume to the dominant tumor region. A rectal balloon inflated with 60 cc of air was used for internal organ immobilization. Five, 8, and 8 patients were sequentially treated with two fractions of 5, 6, or 7 Gy, respectively (normalized total dose in 2 Gy/fraction [NTD(2 Gy)] < 100 Gy, low-dose group), whereas 29 patients received two fractions of 8 Gy each (NTD(2 Gy) > 100 Gy, high-dose group). Androgen deprivation was given to 33 patients. Acute and late toxicities were assessed according to the Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer (RTOG/EORTC) scoring system.Two patients presented with Grade 3 acute urinary toxicity. The 5-year probabilities of >or=Grade 2 late urinary and late low gastrointestinal (GI) toxicity-free survival were 82.2% +/- 7.4% and 72.2% +/- 7.6%, respectively. The incidence and severity of acute or late toxicities were not correlated with low- vs. high-dose groups, pelvic irradiation, age, or treatment with or without androgen deprivation. The 5-year biochemical disease-free survival (b-DFS) and disease-specific survival were 98% +/- 1.9% and 100%, respectively.Intensity-modulated radiotherapy hypofractionated boost dose escalation under stereotactic conditions was feasible, and showed excellent outcomes with acceptable long-term toxicity. This approach may well be considered an alternative to high-dose-rate brachytherapy.