Role of histological regression grade after two neoadjuvant approaches with or without radiotherapy in locally advanced gastric cancer

Abstract

Background: The degree of histopathological response after neoadjuvant therapy in locally advanced gastric cancer (GC) is a key determinant of patients' long-term outcome. We aimed to assess the pattern of histopathological regression after two neoadjuvant approaches and its impact on survival times. Methods: Regression grade of the primary tumour (Becker criteria) and the degree of nodal response by a 4-point scale (grades A-D) were assessed. Grade A - true negative lymph nodes (LNs); grade B and C - infiltrated LNs with any or little evidence of nodal response; and grade D - complete pathological response in a previously infiltrated LN. A favourable pathological response was defined as Becker Ia-b and grade D. Results: From 2004 to 2014, 80 patients with GC (cT3-4/N+ by CT-scan/EUS) were treated with either preoperative chemotherapy (ChT, n=34) or chemoradiation (CRT, n=46). Patients in the CRT group had a higher likelihood of achieving a Becker Ia-b response (58 vs 32%, P=0.001), a grade D nodal regression (30 vs 6%, P=0.009) and a favourable pathological response (23 vs 3%; P=0.019). Patients with a grade D nodal response had a longer 5-year PFS and OS compared with those with a grade B or C response. Patients with a baseline negative LN status had similar outcomes irrespective of the preoperative therapy received (5-year OS; ChT vs CRT, 58 vs 51%, P=0.92). Conclusions: Preoperative chemoradiation increases the likelihood of achieving favourable histopathological features that correlate with a 5-year OS>70% in GC patients.