2171 - Impact of Tumor Length on Locoregional Control following Radical Concurrent Chemoradiotherapy in Esophageal Squamous Cell Carcinoma

Purpose/Objective(s): Tumor length is commonly considered a surrogate for tumor burden in esophageal squamous cell carcinoma and is often perceived to predict inferior outcomes after definitive chemoradiotherapy. However, contemporary real-world evidence in the era of conformal radiotherapy remains limited. We sought to evaluate the impact of baseline tumor length on locoregional control following radical VMAT-based concurrent chemoradiotherapy. Patients were stratified using clinically relevant 6-cm and 8-cm thresholds. The primary objective was to determine whether increasing tumor length independently predicts locoregional failure.

Materials/Methods: This retrospective real-world study included patients with locally advanced esophageal SCC treated between 2018 and May 2025 at a tertiary center. Median age was 59 years, and median tumor length was 6.6 cm (range, 2.5–11). Radiotherapy was delivered using VMAT to a median dose of 59Gy (range, 50.4–64Gy) with concurrent paclitaxel–carboplatin. The same cohort was analyzed using two tumor-length thresholds (6 and 8 cm). Patients were stratified as <6 cm vs =6 cm and <8 cm vs =8 cm. Primary endpoint was LRC; toxicities were graded per CTCAE.

Results: Eighty-one patients were analyzed with median follow-up of 12 months (range, 6–60). For tumors <6 cm, LRC was achieved in 21/41 patients (51.2%) versus 23/40 (57.5%) for =6 cm. Using an 8-cm cutoff, LRC was observed in 32/60 patients (53.3%) with <8 cm tumors and 13/21 (61.9%) with =8 cm tumors. Among patients with LRC, primary tumor location was upper esophagus in 19, middle in 6, lower in 5, and 2 had skip nodal metastases. Acute grade-2 esophagitis occurred in ~80% of patients. Hematologic toxicities were common and mostly low-grade, and treatment compliance remained acceptable.

Conclusion: In this real-world cohort of esophageal SCC treated with VMAT-based radical concurrent chemoradiotherapy, tumor length did not adversely impact locoregional control, even in patients with tumors =6 cm and =8 cm. These findings support the use of curative-intent radical CTRT in patients with large tumor burden and reinforce that tumor length alone should not preclude definitive treatment. Further analysis of distant failures and overall survival is planned.