Comparison of the prognostic difference between ypTNM and equivalent pTNM stages in esophageal squamous cell carcinoma based on the 8th edition of AJCC classification

Objective: With the separate ypTNM stage groupings established in the 8th edition of AJCC staging system for esophageal squamous cell cancer (ESCC), we aimed to evaluate the prognostic difference between ypTNM stage and equivalent pTNM stage. Methods: ESCC patients with surgery alone (cohort 1) and patients with neoadjuvant therapy plus surgery (cohort 2) were enrolled in the study. Results: In p0, pIb, pIIa, pIIb, pIIIa, pIIIb and pIVa stages of cohort 1, the 5-year DFS and OS rates were 100/100%, 80.5/86.2%, 58.9/57.8%, 51.1/52.7%, 36.3/35.8%, 21.5/22.6% and 11.9/18.0%. In ypI, ypII, ypIII and ypIVa stages of cohort 2, the 5-year DFS and OS rates were 60.9/67.0%, 44.3/52.1%, 48.4/43.2% and 0. Patients in ypI stage had a tendency of poorer survival compared with those in pI stage (P=0.024 for DFS, P=0.067 for OS). There was no significant difference in terms of DFS (P=0.335) or OS (P=0.903) between ypII and pII. Patients in ypIII stage had a tendency of better survival compared with those in pIII stage (P=0.015 for DFS, P=0.059 for OS). Patients in ypIVa stage exhibited a significantly poorer OS compared with those in pIVa stage (P=0.038). Conclusions: With down-staged tumor after neoadjuvant therapy, survival of ypI was closed but not reached to the prognosis of equivalent pI, prognosis of ypII was similar to equivalent pII, and survival of ypIII tended to be better compared with equivalent pIII. However, without down-staged ypIVa tumor, the prognosis was worse compared with equivalent pIVa, indicating those patients were primary resistant to prescribed neoadjuvant therapy.