Image-guided IMRT with simultaneous integrated boost as per RTOG 0529 for the treatment of anal cancer.

Abstract

To report on clinical outcomes of simultaneous integrated boost intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy as per Radiation Therapy Oncology Group (RTOG) 0529 protocol in anal cancer patients. Clinical stage T1-T4 N0-N3 anal cancer patients were submitted to concomitant chemoradiation. Patients with cT2N0 disease were prescribed 50.4Gy/28 fractions to the gross tumor planning target volume (PTV) and 42Gy/28 fractions to the elective nodal PTV. Patients staged as cT3-T4/N0-N3 were given 54Gy/30 fractions to the macroscopic anal PTV, while clinical nodes were prescribed 50.4Gy/30 fractions if<3cm or 54Gy/30 fractions if≥3cm; elective nodal PTV was prescribed 45Gy/30 fractions. Two cycles of concomitant 5-fluorouracil and mitomycin C were planned for all patients. Oncological outcomes, acute and late toxicity profiles and pattern of failure were reported. The 3-year colostomy-free survival rate was 64% (95% CI 0.52-0.75). The 3-year local control, disease-free and overall survival rates were 69% (95% CI 0.57-0.79), 71% (95% CI 0.59-0.80) and 79% (95% CI 0.66-0.87), respectively. The cumulative incidence of colostomies was 15.1% (95% CI 8.15-23.88) at 24 months. The cumulative incidence of cancer-specific deaths was 16.4% (95% CI 8.60-26.47) at 36 months. Major acute toxicity consisted of hematological (G3-G4: 26%) and cutaneous (G3-G4: 16%) events. Only one case of≥G3 late toxicity was documented. Simultaneous integrated boost IMRT and concurrent chemotherapy as per RTOG 0529 protocol seems to be safe and feasible with consistent oncological outcomes and a mild acute and late toxicity profile in anal cancer patients.