Area of residual tumor measurement after preoperative chemotherapy as an objective and quantitative method for predicting prognosis of gastric cancer: a single-center retrospective study

Abstract Purpose Anticancer drug therapy plays an indispensable role in the treatment of gastric cancer (GC), and pathologists usually evaluate the effectiveness of therapy using surgically resected specimens. Measurement of the area of the residual tumor (ART) has been reported to be a quantitative and useful method for prognosticating several cancers. Therefore, this study aimed to evaluate the prognostic utility of ART in predicting the outcomes of patients with GC after preoperative chemotherapy. Methods In this single-center retrospective study, we examined the relationship between ART and survival outcomes. We included 92 patients who underwent preoperative chemotherapy followed by radical gastrectomy for GC. Digital images were used to measure the area of residual cancer cells in the largest slice of the tumor of each patient's surgical specimen. We subclassified the patients into two groups: ART-0 (ART < 0.1 mm2, excluding carcinoma in situ) and non-ART-0, and compared their clinicopathological factors and prognosis. Results Significant differences were noted in recurrence-free survival (RFS) and overall survival between ART-0 and non-ART-0. Multivariate analysis revealed that non-ART-0 and ypN-positive status were independent poor prognostic factors for RFS. Subgroup analysis with ypN and ART showed that the patient groups with ypN-negative and ART-0 had a significantly better prognosis (P < 0.001) than the other groups. Conclusion The ART-based assessment is a promising quantitative tool for predicting the prognosis of patients with GC who undergo preoperative chemotherapy and radical gastrectomy.