Revisiting the Radical Radiotherapy-Radiochemotherapy Results in Anal Canal Cancers: (TROD Gastrointestinal Group Study 02-005)

Background and Aim

This study aimed to determine treatment outcomes and factors affecting prognosis in patients diagnosed with anal canal cancer who received radical radiotherapy (RT) or radiotherapy combined with chemotherapy (CT-RT) in radiation oncology centers in Turkey and compare the results with literature.

Material and Method

The study included 193 patients with anal canal cancer reported between 1995 and 2019, of which 162 had complete data. The study was conducted in 11 radiation oncology centers, and a joint database was shared among them. Patients received radiotherapy doses of 45 Gy to 60 Gy. Data analysis was done using SPSS for Windows version 20.

Results

Median follow-up was 48.51 months (2-214). All patients received radiotherapy, and 140 (86.4%) received concurrent chemotherapy. Radiotherapy doses of 50.4 Gy to 60 Gy were administered to 74 patients (45.7%) using 2-dimensional-3-dimensional (2D-3D) conformal therapy and 70 patients (43.2%) using intensity modulated radiotherapy technique (IMRT). Acute phase hematologic toxicity was observed in 62 patients (38.3%), and nonhematologic toxicity in 123 patients (75.9%). The 5-year overall survival (OS) rate was 75.1% and disease-specific survival (DSS) rate was 76.4%. OS without colostomy was achieved in 79,8 % at 5 years, and complete response in 112 patients (69.1%). OS rate was significantly higher in 142 patients with positive response (P < .000) and 112 with complete response (P < .000). Anemia (P < .002), local progression, and systemic progression (P < .000) resulted in lower OS (P < .002). In univariate analysis, factors affecting OS rate were: gender, age, stage, lymph node status, T stage, RT treatment duration, and treatment planning with PET fusion, which were found to be statistically significant. Completing radiotherapy in less than 45 days, concurrent chemotherapy, and continued administration of mitomycin and 5 FU as chemotherapy had a significant positive effect on overall survival. OS rate was higher in patients receiving RT dose of 58 Gy or less and undergoing IMRT planning in radiotherapy. IMRT was associated with lower acute and late side effects.

Conclusion

Radiochemotherapy is the primary treatment for anal canal cancer and advanced radiotherapy techniques may increase survival by reducing side effects and improving treatment continuation. Higher treatment doses require further investigation. The efficacy of treatment can be improved by including patients treated with modern radiotherapy techniques in multicenter prospective studies using new and more effective chemotherapy and immunotherapy agents.