Impact of locoregional treatments in oligometastatic squamous cell anal carcinoma.

Abstract

e15502 Background: Squamous cell anal carcinoma (SCAC) is a rare malignancy with limited therapeutic options in the metastatic setting. While systemic therapy represents the standard of care, the role of curative-intent locoregional treatments (LRT) in metastatic SCAC (mSCAC) is supported by limited clinical evidence. We investigated the impact of curative-intent LRT on survival outcomes in patients (pts) with mSCAC. Methods: This retrospective, single-center study included adult pts diagnosed with oligometastatic SCAC treated at the Veneto Institute of Oncology–IRCCS (Padua, Italy) between Jan-2015 and Dec-2024. Comprehensive clinical, pathological and treatment-related data were collected. Oligometastatic disease was defined as the presence of a limited number of metastatic lesions amenable to complete LRT, as assessed by a dedicated multidisciplinary tumor board (MTB). Curative-intent LRT included surgery, radiotherapy (RT) and microwave ablation. Disease-free survival (DFS), progression-free survival (PFS), and overall survival (OS) were estimated using the Kaplan–Meier method. Associations between clinicopathological variables and survival outcomes were evaluated using univariable and multivariable Cox proportional hazards models. To mitigate immortal time bias, curative-intent LRT was modeled as a time-dependent covariate. Results: Among over 300 cases of SCAC discussed at a dedicated MTB, 67 patients with metastatic disease were included; 27 (40.3%) underwent curative-intent LRT. Median follow-up was 58 months. Pts receiving LRT experienced a significantly prolonged OS compared with those who did not (median OS 56.3 vs 19.0 months; HR 0.22, 95% CI 0.12–0.45; p < 0.0001). This association remained significant in time-dependent analyses (HR 0.36, 95% CI 0.16–0.78; p = 0.010) and in multivariable models adjusting for metastatic timing and ECOG performance status (HR 0.18, 95% CI 0.08–0.47; p < 0.0001). Among patients receiving LRT, median DFS was 5.9 months, with a subset achieving durable disease control. In pts with synchronous metastatic disease treated with definitive concurrent chemoRT to the primary tumor, durable local control was associated with improved OS (median OS 41 vs 10 months). Conclusions: In this real-world cohort, curative-intent LRT were independently associated with prolonged OS in carefully selected pts with mSCAC. These findings support the potential value of integrating LRT into a personalized, multimodal treatment strategy guided by multidisciplinary evaluation. Prospective studies are warranted to refine patient selection, optimize treatment sequencing, and define the integration of LRT emerging systemic therapies, including immunotherapy.