Simultaneous Integrated Boost by Volumetric Modulated Arc Therapy (VMAT) with Concurrent Mitomycin and Capecitabine in Anal Canal Carcinoma

Abstract

Background: Combined treatment with radiotherapy and chemotherapy is the standard approach in non-metastatic anal carcinoma. Intensity-modulated radiotherapy and volumetric modulated arc therapy are currently the most accepted radiation techniques. We intend to report the clinical outcomes of patients that have been treated with volumetric modulated arc therapy concomitant with mitomycin C and capecitabine. Methods: This was a retrospective analysis of 11 patients diagnosed with anal carcinoma who received volumetric modulated arc therapy and a simultaneous integrated boost with concurrent chemotherapy. The chemotherapy protocol consisted of intravenous infusions of mitomycin C (12 mg/m2) on days 1 and 29, and oral capecitabine (825 mg/m2) twice daily with radiotherapy treatment. Results: Most patients had stage IIIB (45.4%) disease. The majority of patients (63.7%) received a dose of 59.4Gy per 33 fractions to the primary tumor and enlarged lymph nodes (median dose: 59.4 Gy; range: 54 Gy-61 Gy). The overall treatment period ranged between 34-56 days. All patients received the planned chemotherapy protocol of two cycles with the exception of one patient who received one cycle due hematologic toxicity and intolerance. Grade 3 skin toxicity occurred in three (27.3%) patients followed by grade 3 gastrointestinal toxicities in 18.2% of patients. Grade 2 anemia (18.2%), neutropenia (27.3%), and thrombocytopenia (27.3%) were observed in eight patients. Complete response was achieved in 90.9% of patients. Patients had an overall one-year survival of 89% and overall 3-year survival of 71% (95% CI: 20.75%- 38.49%). After the median follow up period of 12 months, patients had a progression-free survival of 75% (95% CI: 21.29%-38.6%) and 2-year colostomy free survival of 68% (95% CI: 17.2%-32.1%). Conclusion: Volumetric modulated arc therapy is a safe and effective modality of intensity modulated radiotherapy when combined with chemotherapy (mitomycin C and capecitabine) in anal cancer patients.