Extracapsular spread (ECS) is one of the most significant predictors of treatment outcome in oral squamous cell carcinomas (OSCCs). However, the mechanism of occurring ECS remains unclear. To solve this problem, we observed the status of ECS histopathologically and attempted to classify the status of ECS. In addition, we examined the correlation between ECS status and prognosis of the OSCC patients. Nineteen OSCC patients who had at least one node with ECS (ECS+) among pathologically positive nodes (pN+) were examined for this study. All patients underwent primary surgical excision without preoperative treatment at the Section of Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, from August 2004 to November 2009. With respect to 51 ECS+ nodes of those patients, we measured minor axis (MA) of the nodes, tumour occupied area of the intra- and extra- nodes at each maximum divided surface. We then defined ‘Tumour Ratio (TR)’ as the ratio of intra- to extra-node area of the tumour. When 0.5 of TR and 10 mm of MA were determined as the cutoff point, it was possible to classify all ECS+ nodes into 4 types. When the ECS type of each patient was defined as the dominant type of ECS observed in the patient, the patients could be classified into 3 groups. To reveal the influence of ECS status on survival, the survival data of the patients were compared between these three groups using Kaplan–Meier analysis. This analysis revealed that the prognosis of the group with TR□,,0.5 and MA□..10 mm tended to be worse than the other groups on overall survival. In this study, it was suggested that the prognosis of the OSCC patients depended on the status of ECS. The mechanism of occurring ECS in individual ECS type might be different.
Classification of extracapsular spread of the lymph node metastasis in oral cancer
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