Introduction: We aimed to analyze the clinical and histological effects of chemotherapy in superficial esophageal squamous cell carcinoma (SESCC). Methods: We analyzed tumor samples from five patients with cT1bN1M0 who underwent subtotal esophagectomy following two courses of a new triplet chemotherapy regimen including docetaxel, cisplatin, and 5-fluorouracil (DCF). To assess the histological effects of chemotherapy, resected specimens were analyzed by macroscopic examination, hematoxylin & eosin (HE) staining, immunohistochemical (IHC) staining (p53, Ki-67 and cytokeratin) and periodic acid-Schiff (PAS) staining. Results: All five patients had a pathological T stage of T0/1a-LPM/1a-MM/1b (1/2/1/1) and histological grade of grade1a/1b/2/3 (1/1/2/1). Endoscopic examination revealed substantial shrinkage of lugol-voiding lesions (LVLs) in all cases. One case showed complete LVL disappearance, and resected specimen examination confirmed pathological complete response (pCR). IHC and PAS staining revealed that most initial LVLs were PAS-negative. Obvious viable cells were confirmed in two cases. The other three cases exhibited nuclear atypia and strong expression of p53 and Ki-67 in the basal layer of mucosa or lamina propria mucosae, even though the superficial layer of mucosa showed no obvious LVLs with PAS-positive. p53-positive lesions were also observed in Ki-67-positive. This indicated discordance between the endoscopic findings and histopathological evaluation. Conclusion: DCF chemotherapy alone had a substantial therapeutic effect on SESCC in all cases. However, despite the normal appearance of the mucosal surface, viable cancer cells remained below the basal layer of mucosa. Careful attention should be paid when diagnosing clinical CR, or securing a resection margin of SESCC after DCF chemotherapy.
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