Definitive irradiation and chemotherapy for radiosensitization in management of anal carcinoma: interim report on Radiation Therapy Oncology Group study no. 8314

Abstract

Following documented evidence of the synergism of 5-fluorouracil (5-FU) and radiation therapy and an additive effect with mitomycin and irradiation, pilot studies have demonstrated the potential for definitive radiation therapy in the management of squamous cell and basaloid carcinomas of the anal canal, allowing sphincter preservation. Our study explored the long-term effectiveness of combined therapy at this disease site and examined the feasibility of a Radiation Therapy Oncology Group study involving concomitant radiation therapy and chemotherapy. Between 1983 and 1987, 79 assessable patients with any primary tumor stage of anal canal carcinoma were treated by external-beam irradiation combined with mitomycin given by bolus iv injection and 5-FU given by continuous infusion. Radiation was delivered to the perineum and pelvis to a total dose of 4,080 cGy in 4.5-5 weeks. The inguinal nodal areas received 4,080 cGy, calculated at a 3-cm depth in the center of the nodal area. A 96-hour infusion of 5-FU was started on days 2 and 28 of the irradiation at a dose of 1,000 mg/m2 over 24 hours, and a bolus injection of mitomycin was administered on day 2 at a dose of 10 mg/m2. The overall survival rates are 97% at 1 year and 73% at 3 years. Patients with lesions less than 3 cm in diameter and those treated strictly according to the protocol did significantly better than those with larger lesions and those whose treatment did not comply with the protocol. The interim outcome of the study demonstrates that this combined therapy is effective for patients with anal cancer and allows preservation of the sphincter and of sexual function.