Role of nodal skip metastasis in patients with mid-thoracic oesophageal squamous cell carcinoma: a propensity score matching study

OBJECTIVES Nodal skip metastasis (NSM) is a common phenomenon in mid-thoracic oesophageal squamous cell carcinoma (MT-OSCC); however, the prognostic implications of NSM in patients with MT-OSCC remain unclear. METHODS This retrospective study enrolled 300 patients with MT-OSCC who underwent radical oesophagectomy and who had pathologically confirmed lymph node metastasis from January 2014 to December 2016. The patients were divided into 2 groups according to the presence or absence of NSM. Propensity score matching was applied to minimize patient selection bias. The impact of NSM on overall survival (OS) was assessed by Kaplan-Meier and multiple Cox proportional hazards analyses. The median follow-up time was 57 months. RESULTS The NSM rate in the entire cohort was 22.0% (66/300). Pathological N (pN) stage (P < 0.001) and sex (P = 0.001) were identified as significant independent risk factors for NSM. NSM was more frequent in pN1 compared with pN2 patients (87.9% vs 12.1%, P < 0.001) and no NSM was found in pN3. NSM(+) patients had better prognoses than NSM(-) patients (Kaplan-Meier; 3-year OS, 62.1% vs 34.1%, P < 0.001). Propensity score matching produced 51 matched pairs, and the 3-year OS was still better in the NSM(+) compared with the NSM(-) group (66.7% vs 40.0%, P = 0.025). Multivariable Cox analysis confirmed NSM(+) as an independent factor favouring OS in patients with MT-OSCC. CONCLUSIONS NSM usually occurs at pN1 stage in patients with MT-OSCC, and is associated with a favourable prognosis.