Treatment, outcome, and prognostic factors in non-metastatic anal cancer: The French nationwide cohort study FFCD-ANABASE.

Introduction: International guidelines regarding the treatment of squamous cell carcinoma of the anus (SCCA) recommend intensity-modulated radiotherapy (IMRT) combined with mitomycin-based chemotherapy (CT). The French FFCD-ANABASE cohort aimed at evaluating clinical practices, treatment, and outcomes of SCCA patients.

Methods: This prospective multicentric observational cohort included all non-metastatic SCCA patients treated in 60 French centers from January 2015 to April 2020. Patients and treatment characteristics, colostomy-free survival (CFS), disease-free survival (DFS), overall survival (OS), and prognostic factors were analyzed.

Results: Among 1015 patients (male: 24.4 %; female: 75.6 %; median age: 65 years), 43.3 %presented with early-stage(T1-2, N0) and 56.7 % with locally advanced stage (T3-4 or N + ) tumors. IMRT was used for 815 patients (80.3 %) and a concurrent CT was administered in 781 patients, consisting of mitomycin-based CT for 80 %. The median follow-up was 35.5 months. DFS, CFS, and OS at 3 years were 84.3 %, 85.6 %, and 91.7 % respectively in the early-stage group compared to 64.4 %, 66.9 %, and 78.2 % in the locally-advanced group (p < 0.001). In multivariate analyses, male gender, locally-advanced stage, and ECOG PS ≥ 1 were associated with poorer DFS, CFS, and OS. IMRT was significantly associated with a better CFS in the whole cohort and almost reached significance in the locally-advanced group.

Conclusion: Treatment of SCCA patients showed good respect for current guidelines. Significant differences in outcomes advocate for personalized strategies by either de-escalation for early-stage tumors or treatment intensification for locally-advanced tumors.