Gastrectomy for invasive micropapillary carcinoma is associated with poorer disease-free and disease-specific survival

Background Invasive micropapillary carcinoma (IMPC) is a relatively rare subtype of gastric adenocarcinoma and has aggressive histopathologic characteristics, including lymphatic and vascular invasion. However, the associated long-term survival outcomes remain unclear. This study aimed to compare the clinicopathological characteristics and prognosis of gastric adenocarcinoma with and without IMPC using propensity score-matched (PSM) analysis. Methods Patients with gastric adenocarcinoma who underwent gastrectomy between 2006 and 2015 were included in the analysis. PSM analysis was performed to compensate for the background heterogeneity between the groups. The primary endpoint was disease-free survival (DFS) after gastrectomy, and the secondary endpoints were disease-specific survival (DSS) and recurrence pattern. Results Of 882 patients who underwent gastrectomy for gastric adenocarcinoma, with a follow-up duration greater than 36 months, 35 were diagnosed as having gastric adenocarcinoma with IMPC. After PSM, 70 patients, including 35 with IMPC and 35 without IMPC, were selected. Gastric adenocarcinoma with IMPC is characterized by lymphatic invasion (94% versus 69%, p = 0.012). Patients with IMPC had significantly poorer DFS than those without IMPC, with 3-year DFS rates of 62.2% and 93.4% ( p = 0.003), respectively. Furthermore, a significant difference was also observed in DSS ( p = 0.016); patients with IMPC more frequently developed liver metastasis (20%) than those without IMPC (3%, p = 0.006). Conclusions Resected gastric carcinoma with IMPC was associated with poorer DFS and DSS; furthermore, an increased rate of lymphatic invasion and liver metastasis was noted than in cases without IMPC.