OA03-RF01.02. Clinical Significance of Endoscopic Sub-Classification “Remarkable Response (RR)” After Neoadjuvant DCF Therapy in Esophageal Squamous Cell Carcinoma

Topic Esophageal Cancer: Adjuvant and Neo-Adjuvant Therapies Background In esophageal squamous cell carcinoma (ESCC), the importance of endoscopic assessment of tumor response after neoadjuvant chemotherapy has been reported. The Japanese Classification of Esophageal Cancer has introduced a new endoscopic sub-classification, “Remarkable response (RR),” but its clinical significance has not been fully clarified. Methods We retrospectively analyzed patients with resectable locally advanced ESCC (cT2–3/N0–3/M0–1, UICC-TNM 8th edition) who received ≥1 cycle of neoadjuvant docetaxel, cisplatin, and fluorouracil (DCF) therapy followed by surgery between 2015 and 2020 at our institution. Patients enrolled in JCOG1109, those without evaluable endoscopic images, those with >56 days from DCF completion to surgery, or those without R0 resection were excluded. Two endoscopists retrospectively evaluated pre- and post-treatment endoscopic images and classified cases into three groups: 1) non-CR/non-PD (RR), 2) non-CR/non-PD (non-RR) and 3) PD. Recurrence-free survival (RFS), overall survival (OS), and the proportion of histological responders (grade 2–3: moderately or markedly effective) were assessed. Results A total of 114 patients were included (median age 66.5 years, 91 mens). Endoscopic evaluation classified 63 patients as RR and 51 patients as non-RR, with no patients classified as PD. During a median follow-up of 42.6 months, 3-year RFS rates were 62.2% in the RR group and 49.0% in the non-RR group (P=0.098). Three-year OS rates were significantly higher in the RR group than in the non-RR group (76.9% vs. 53.0%, P=0.026). Histological responders (grade 2–3) was observed in 71.4% (45/63) of RR cases compared with 9.8% (5/51) of non-RR cases. Conclusion Endoscopic sub-classification “RR (Remarkable response)” may be useful for prognostic stratification and predicting histological response after neoadjuvant DCF therapy. We are planning multicenter studies with larger cohorts that include other treatment regimens, as well as chemoradiotherapy to further evaluate the clinical significance of RR.