Significance of Intramural Metastasis in Patients with Esophageal Squamous Cell Carcinoma: An Indicator of Aggressive Cancer Behavior

BackgroundIntramural metastasis (IM) is occasionally noted in patients with esophageal squamous cell carcinoma (ESCC). However, few recent studies have investigated the clinicopathological characteristics of IM and its survival impact. The present study aimed to clarify the clinicopathological and prognostic significance of IM in patients with ESCC.MethodsWe retrospectively examined 918 consecutive patients who underwent curative intent esophagectomy for ESCC. IM was defined as a pathologically confirmed metastatic lesion, which was clearly separate from the primary tumor and located within the esophageal or gastric wall. The clinicopathological characteristics and survival impact of IM were evaluated. A propensity score-matched analysis was performed to further elucidate the prognostic impact of IM.ResultsAmong 918 patients, 46 (5.0%) had IM. Advanced tumors were significantly more frequent in patients with IM than in those without IM. The curative resection rate was lower in patients with IM (P=0.001). Overall survival (OS) and disease-specific survival (DSS) were worse in patients with IM (both P<0.001). In multivariate Cox proportional hazard analysis, IM presence was an independent poor prognostic indicator for OS and DSS (both P<0.001). After propensity score matching, advanced tumors according to pathological N stage and lymphatic invasion were more frequent in patients with IM (P=0.015 and 0.004, respectively). Additionally, OS and DSS were different between patients with and those without IM (both P=0.002).ConclusionsIM from ESCC is a local indicator of lymphatic invasion and advanced cancer, as well as an independent factor for poor prognosis.