Moderate Hypofractionation with Simultaneous Integrated Boost in Prostate Cancer: Long-term Results of a Phase I-II...

Area of Science:

• Radiation Oncology
• Medical Physics
• Oncology

Background:

• Prostate cancer treatment often involves radiotherapy.
• Image-guided radiotherapy (IGRT) enhances treatment precision.
• Hypofractionation and simultaneous integrated boost (SIB) are advanced techniques to optimize dose delivery.

Purpose of the Study:

• To evaluate the 5-year outcomes and late toxicity of prostate cancer patients treated with IGRT tomotherapy using a moderate hypofractionated SIB approach.
• To assess the efficacy and safety of this technique across different risk groups (low, intermediate, high).

Main Methods:

• A cohort of 211 prostate cancer patients (low, intermediate, high risk) treated between 2005-2011.
• Moderate hypofractionated intensity-modulated radiotherapy with SIB, delivering up to 74.2 Gy/28 fractions.
• Daily MVCT for image guidance and concurrent androgen deprivation therapy.
• Assessment of 5-year biochemical relapse-free survival (bRFS), cancer-specific survival (CSS), overall survival, and late gastrointestinal (GI) and genitourinary (GU) toxicity (CTCAE.v3).

Main Results:

• After a median 5-year follow-up, 5-year bRFS was 93.7% (low risk: 94.6%; intermediate: 96.2%; high: 91.1%).
• Overall survival was 88.6% and CSS was 97.5%.
• Late toxicity (≥ grade 3) was acceptable: GU 5.9% (≥ grade 2: 20.2%), GI 6.3% (≥ grade 2: 17%), with lower rates at last follow-up (GU: 1.9%, GI: 1.9%). Acute GU toxicity (≥ grade 2) and prior surgery predicted late toxicity.

Conclusions:

• Image-guided tomotherapy with a moderate hypofractionated SIB approach provides satisfactory 5-year outcomes and an acceptable toxicity profile for prostate cancer patients.
• This combined approach, including prophylactic lymph node irradiation, is effective even for high-risk patients.