Oncological impact of unexpected horizontal tumor spread in gastric cancer that requires total gastrectomy.

Abstract

Gastric cancer often exhibits discrepancies between the gross and pathological tumor boundaries, and the degree of discrepancy may be a tumor characteristic. However, whether these discrepancies influence oncological outcomes remains unclear. The data of patients who underwent total gastrectomy for gastric cancer from 2005 to 2018 were collected. A new parameter, ΔPM, which corresponds to the length of the discrepancy between the gross and pathological proximal boundaries, was calculated and the patients were divided into two groups: patients with long ΔPM and those with short ΔPM. Oncological outcomes were compared between the two groups. A length of 8mm was determined as the cutoff value for long or short ΔPM. Tumor size, growth pattern, pathological type, depth, and esophageal invasion were associated with ΔPM > 8mm. Overall survival of the ΔPM > 8mm group was significantly worse than that of the ΔPM ≤ 8mm group (5-year overall survival: 58% vs 78%; p < 0.0001). Multivariate analysis revealed that ΔPM > 8mm was an independent risk factor for poor survival and peritoneal metastasis. The likelihood ratio test revealed a significant interaction between pT status and ΔPM (p = 0.0007). Circumferential involvement and gross esophageal invasion were poorer survival factors in the ΔPM > 8mm group. ΔPM > 8mm is related to several clinicopathological characteristics and is an independent risk factor for poorer survival and peritoneal metastasis but not local recurrence. ΔPM > 8mm combined with circumferential involvement or esophageal invasion is associated with relatively poor survival outcomes.