Local Invasion Patterns Characterized by SARIFA and Tumor Budding Differ and Have Distinct Prognostic Significance in Esophageal Adenocarcinoma and Squamous Cell Carcinoma

Both esophageal squamous cell carcinoma (ESQCC) and adenocarcinoma (EAC) are known to have poor prognosis. We aimed to investigate the invasion front areas of 57 ESQCC and 43 EAC cases to find histological signs of metastatic progression. Tumor cell clusters with different cell counts, including tumor buds (TBs) and poorly differentiated clusters (PDCs), were assessed. The presence of the recently described Stroma AReactive Invasion Front Area (SARIFA) phenomenon, which defines a direct contact between tumor cells and adipocytes, was more frequently observed in EAC than in ESQCC (<i>p</i> = 0.004). In adenocarcinomas, a higher prevalence of SARIFA was observed in tumors with a higher number of small clusters (TBs and small PDCs; <i>p</i> < 0.001); furthermore, both the high number of TBs (<i>p</i> = 0.016) and the presence of SARIFA (<i>p</i> = 0.001) correlated with a higher pT stage. SARIFA positivity in EAC (<i>p</i> = 0.011) and high TB in ESQCC (<i>p</i> = 0.0006) were found to be independent prognostic factors for lymph node metastases. Moreover, in ESQCC, the higher absolute number of both TBs and PDCs was associated with shorter overall survival (<i>p</i> = 0.0269 and <i>p</i> = 0.0377, respectively). Our results suggest that the histological subtypes of esophageal cancer behave differently, namely, that different features of the invasion front are of prognostic significance.