Effect of histologic differences between biopsy and final resection on treatment outcomes in early gastric cancer

Background and study aims: Biopsy-based histologic diagnosis is important in determining the treatment strategy for early gastric cancer (EGC). However, there are few studies on how histologic discrepancy may affect patients’ treatment outcomes. We aimed to investigate the impact of histopathologic differences between biopsy and final specimens from endoscopic resection (ER) or gastrectomy on treatment outcomes in patients with EGC. We also examined the predictive factors of histologic discrepancy. Patients and methods: We analyzed the data of 1851 patients with EGC treated with ER or gastrectomy. We compared the histology between biopsies and final resected specimens from ER or gastrectomy. We also examined changes in treatment outcomes according to histologic differences. Results: Histologic discrepancy was observed in 11.9% of patients in the ER group and 10.7% of those in the gastrectomy group. In patients treated with ER who showed histologic discrepancy, 80.9% showed differentiated-type EGC (D-EGC) on biopsy but undifferentiated-type-EGC (UD-EGC) after ER, of which 78.9% were non-curative resection. In patients treated with gastrectomy who showed histologic discrepancy, 39% showed UD-EGC on biopsy but showed D-EGC after gastrectomy. A total of these patients had absolute and expanded indications for ER. Moderately differentiated and poorly differentiated adenocarcinoma on biopsy were predictive factors of histologic discrepancy in UD-EGC and D-EGC on final resection, respectively. Conclusions: About 10% of patients showed histologic discrepancy between biopsy and final resection with ER or gastrectomy. Histologic discrepancy can affect treatment outcomes, such as non-curative resection in ER or missing the opportunity for ER in gastrectomy.