Outcomes of elderly patients treated with chemoradiotherapy for anal squamous cell carcinoma: a multicenter study of the German cancer consortium - radiation oncology group (DKTK-ROG)

Background Older patients with anal squamous cell carcinoma (ASCC) are underrepresented in prospective studies evaluating chemoradiotherapy (CRT). We evaluated patient−/tumor−/treatment characteristics and oncologic outcomes in older patients treated with CRT in a large retrospective multicenter cohort study of the DKTK-ROG. Materials and Methods Patients with localized ASCC treated with CRT between 2004 and 2018, were retrospectively analyzed. Older patients were defined as age ≥ 70 years at CRT initiation. Freedom from recurrence (FFR) and overall survival (OS) were analyzed using Kaplan-Meier estimates, competing-risk analyses, and Cox regression models. Results A total of 683 patients were analyzed, including 180 older patients (≥70 years, 26%). The 3-year FFR and OS rates for the entire cohort were 80.0% (95% CI, 76.9–83.3%) and 87.1% (95% CI 84.5–89.9%), respectively. Competing risk regression for locoregional failure including non complete response or distant metastases with death as competing risk revealed no significant difference between both groups ( p = 0.5, p = 0.9, respectively). In contrast, older patients demonstrated inferior OS ( p < 0.001). In multivariable analysis, advanced age remained associated with inferior OS (HR 2.51, 95% CI 1.73–3.64, p < 0.001), whereas no association between older age and FFR was observed (HR 1.04, 95% CI 0.69–1.58, p = 0.856); advanced T category and nodal involvement remained the dominant prognostic factors for worse FFR. Interpretation Definitive CRT provides meaningful oncologic control in selected older patients with localized ASCC. Chronological age alone should not preclude curative-intent treatment. Future studies should integrate geriatric assessment to better individualize treatment strategies in older patients.