Objective: Hypopharyngeal cancer is a head and neck cancer with a poor prognosis, and most cases show metastases on diagnosis. Cervical lymph node (LN) metastasis is a poor prognostic factor in hypopharyngeal cancer patients. The identification of risk factors for LN metastasis can help guide surgical treatment strategies for these patients.
Methods: This retrospective study included 93 superficial hypopharyngeal cancer patients with 109 histopathologically examined lesions treated by endoscopic resection between January 2007 and December 2017. Tumor thickness quantification, quantification of budding nests, immunostaining and other histopathological analyses in paraffin-embedded, formalin-fixed tissue sections (3-μm) of surgical specimens were performed by a certified pathologist.
Results: Cervical LN metastasis was positive in 18 out of 93 cases (19.3%) and 18 out of 109 lesions (16.5%). No differences were detected in patient characteristics between LN-positive and LN-negative cases, except for tumor thickness, which was significantly larger in LN-positive cases (3119.4±602.2μm vs. 1015.5±129.6μm, respectively; p<0.0001). Univariate analysis showed that tumor thickness ≥1000μm (odds ratio: 5.559, p=0.003), lesions with high budding grade (odds ratio: 5.188, p=0.01) and vascular invasion (odds ratio: 12.710, p=0.007) were significantly associated with cervical LN metastasis. Multivariate analysis revealed tumor thickness≥1000μm as the most significant risk factor for cervical LN metastasis in superficial hypopharyngeal cancer (odds ratio: 3.639, p=0.04).
Conclusions: We demonstrate for the first time that high budding grade may serve as powerful predictors of LN metastasis and tumor thickness ≥1000μm is a significant risk factor for LN metastasis of superficial hypopharyngeal cancer. These results should be further examined in future larger scale studies.
Keywords: Endoscopic submucosal resection; Hypopharyngeal neoplasms; Lymphatic metastasis; Risk factors.
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