Aims The prognostic significance of infiltration growth pattern (INF) in patients with gastric cancer (GC) remains controversial. In the present study, we evaluated the impact of INF pattern on the prognosis of patients with advanced GC.

Methods A total of 1455 patients with advanced GC who underwent curative gastrectomy in our institution were retrospectively analysed. All patients were histopathologically classified as INFa/b and INFc pattern according to the Japanese Classification of Gastric Cancer. The prognostic difference between two patterns was compared and clinicopathological features were analysed.

Results The prognosis of the patients with INFc pattern was poorer than that of those with INFa/b pattern (5-year disease-free survival, INFa/b: 48.4% vs INFc: 33.5%, p < 0.001), even when they were stratified according to lymph node metastasis and the tumour, node, metastases stage. In addition, the subgroup analysis indicated that INFc pattern was significantly associated with poorer prognosis of T2–T3 stage patients (T2, INFa/b: 72.7% vs INFc: 55.4%; T3, INFa/b: 47.4% vs INFc: 33.5%; p<0.001). However, a similar result was not observed among T4a stage patients (INFa/b: 26.8% vs INFc: 24.8%, p>0.05). The prognosis of T2 stage patients with INFc pattern was similar to that of T3 stage patients with INFa/b pattern (p>0.05). Also, there was no significantly prognostic difference between T3 stage patients with INFc pattern and T4a stage patients (p>0.05). The multivariate analysis indicated that INF pattern was an independent prognostic factor for patients with advanced GC (HR 1.259, 95%CI 1.089 to 1.454).

Conclusion In view of its prognostic significance, histopathological evaluation of INF pattern in surgically resected specimens should be recommended in patients with advanced GC.