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

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 ۱۱ 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 (۱۲ mg/m۲) on days ۱ and ۲۹, and oral capecitabine (۸۲۵ mg/m۲) twice daily with radiotherapy treatment. Results: Most patients had stage IIIB (۴۵.۴%) disease. The majority of patients (۶۳.۷%) received a dose of ۵۹.۴Gy per ۳۳ fractions to the primary tumor and enlarged lymph nodes (median dose: ۵۹.۴ Gy; range: ۵۴ Gy-۶۱ Gy). The overall treatment period ranged between ۳۴-۵۶ 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 ۳ skin toxicity occurred in three (۲۷.۳%) patients followed by grade ۳ gastrointestinal toxicities in ۱۸.۲% of patients. Grade ۲ anemia (۱۸.۲%), neutropenia (۲۷.۳%), and thrombocytopenia (۲۷.۳%) were observed in eight patients. Complete response was achieved in ۹۰.۹% of patients. Patients had an overall one-year survival of ۸۹% and overall ۳-year survival of ۷۱% (۹۵% CI: ۲۰.۷۵%- ۳۸.۴۹%). After the median follow up period of ۱۲ months, patients had a progression-free survival of ۷۵% (۹۵% CI: ۲۱.۲۹%-۳۸.۶%) and ۲-year colostomy free survival of ۶۸% (۹۵% CI: ۱۷.۲%-۳۲.۱%). 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.

Keywords:

Anal Cancer , Volumetric , Modulated Arc Therapy , Mitomycin C , Capecitabine