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Scientific article
English

Hypofractionated boost to the dominant tumor region with intensity modulated stereotactic radiotherapy for prostate cancer: a sequential dose escalation pilot study

Publication date2010
Abstract

PURPOSE: 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. METHODS AND MATERIALS: 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. RESULTS: Two patients presented with Grade 3 acute urinary toxicity. The 5-year probabilities of ≥ 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. CONCLUSION: 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.

Keywords
  • Aged
  • Androgen Antagonists/therapeutic use
  • Feasibility Studies
  • Gastrointestinal Tract/radiation effects
  • Humans
  • Immobilization/instrumentation/methods
  • Male
  • Pilot Projects
  • Prostate
  • Prostatic Neoplasms/drug therapy/pathology/*radiotherapy
  • Radiation Injuries/pathology
  • Radiation Tolerance
  • Radiotherapy Dosage
  • Radiotherapy, Intensity-Modulated/adverse effects/*methods
  • Tumor Burden
  • Urinary Bladder/radiation effects
Citation (ISO format)
MIRALBELL, Raymond et al. Hypofractionated boost to the dominant tumor region with intensity modulated stereotactic radiotherapy for prostate cancer: a sequential dose escalation pilot study. In: International journal of radiation oncology, biology, physics, 2010, vol. 78, n° 1, p. 50–57. doi: 10.1016/j.ijrobp.2009.07.1689
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ISSN of the journal0360-3016
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