在日本，大型 3 型胃癌（直径 ≥ 8 cm）和 4 型胃癌被任意组合为一个实体。然而，这两种类型在肿瘤学上是否相似仍不清楚。本研究旨在澄清这个问题。在这项回顾性研究中，我们分析了 2010 年至 2014 年间来自 9 个机构的 3,575 名接受胃切除术的患者的数据库。使用倾向评分来平衡显着变量，我们比较了预后和肿瘤复发情况。接受 R0 切除的 T3/T4 患者中，分别有 75 例和 73 例患有较大的 3 型和 4 型肿瘤。 4 型肿瘤患者的总生存率显着低于大型 3 型肿瘤患者（风险比 [HR] 1.77；95% 置信区间 [CI] 1.14-2.74）。然而，在大型3型肿瘤中，分化型和未分化型组织学类型之间的预后存在显着差异。倾向评分匹配后，对未分化表型的大型3型和4型进行了比较，各39名患者。两组的总生存率（HR 1.28；95% CI 0.73-2.25）和无复发生存率（HR 1.34；95% CI 0.80-2.27）相似。腹膜复发率（35.9% vs. 46.1%，P = 0.36）和淋巴结复发率（25.6% vs. 12.8%，P = 0.15）无统计学差异。 未分化表型和类型的大3型肿瘤4个肿瘤在肿瘤学上相似。该亚组可被视为未来临床试验的新实体。© 2024。作者。

Large type 3 (diameter ≥ 8 cm) and type 4 gastric cancers have been arbitrarily combined in Japan as a single entity. However, whether these two types are oncologically similar remain unclear. This study aimed to clarify this issue.In this retrospective study, we analyzed a database of 3,575 patients from nine institutions who underwent gastrectomy between 2010 and 2014. Using propensity scores to balance significant variables, we compared prognoses and tumor recurrences.Of patients with clinical T3/T4 who underwent R0 resection, 75 and 73 had large type 3 and 4 tumors, respectively. Patients with type 4 tumors had significantly lower overall survival rates than those of patients with large type 3 tumors (hazard ratio [HR] 1.77; 95% confidence interval [CI] 1.14-2.74). However, among the large type 3 tumors, a remarkable difference in prognosis was observed between the differentiated and undifferentiated histological types. A comparison was made between large type 3 with undifferentiated phenotype and type 4, each with 39 patients after propensity score matching. Outcomes in both groups were similar in terms of overall survival (HR 1.28; 95% CI 0.73-2.25) and relapse-free survival (HR 1.34; 95% CI 0.80-2.27). No statistically significant differences were observed in the incidence of peritoneal recurrence (35.9% vs. 46.1%, P = 0.36) and lymph node recurrence (25.6% vs. 12.8%, P = 0.15).Large type 3 tumors with undifferentiated phenotype and type 4 tumors were oncologically similar. This subgroup could be considered as a new entity for future clinical trials.© 2024. The Author(s).