Objectives: Metastasis in a single lymph node without adverse tumour factors and perineural invasion has been assigned to a lower risk category by the ASCO recommendations of 2019. We analyzed patients with a single positive node with a view to identifying high risk features and their impact on prognosis within this subgroup.
Materials and methods: The study retrospectively analyzed 707 patients with OSCC. Descriptive statistics were used to compare distribution of clinicopathologic risk features between 323 N0 and 121 single node positive (Ns) patients. The Ns group was further analyzed for the impact of clinicopathologic factors on disease free (DFS) and overall survival (OS) using univariate and multivariate models.
Results: The Ns group exhibited greater depth of invasion compared to the N0 group and significantly higher proportion of lymphovascular invasion (LVI), perineural invasion (PNI) and poorly differentiated tumors. Within the Ns group, primary tumor localised to the gingivobuccal subsite (HR 2.55, 1.18-5.52 95%CI, p = 0.02) and PNI (HR 2.55, 1.14-5.62, 95%CI p = 0.02) exhibited poor DFS. PNI also contributed to poor OS (HR 2.86, 1.27-6.47 95%CI, p = 0.01). Uninvolved margins (HR 0.46, 0.22-0.96 95%CI, p = 0.04) and chemoradiation (HR 0.18,0.05-0.68 95% CI, p = 0.01) improved OS.
Conclusion: Significant differences are noted in the prevalence of pathologic risk factors between the single node positive and node negative groups. Within the single node positive group, tumour factors like the gingivobuccal subsite, PNI and margin positivity impacted survival. Among nodal factors, deposit size of 12 mm or more and presence of ENE are pointers to poor prognosis. These patients would benefit from adjuvant treatment.
Keywords: Node positive neck; Oral cancer; Pathologic risk factors; Prognostic factors; Single positive node.
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