Positive lymph node ratio predicts adverse prognosis for patients with lymph nodes metastatic hypopharyngeal squamous cell carcinoma after primary surgery

BACKGROUND: Positive lymph node ratio (LNR) is associated with the prognosis of many cancers. However, its prognostic value in patients with hypopharyngeal squamous cell carcinoma (HSCC) is unclear due to the rarity of HSCC. This study aimed to investigate the prognostic value of LNR in HSCC using the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: Data spanning 2004 to 2015 of eligible HSCC patients were retrospectively retrieved from the SEER database. Clinicopathological data, including age at diagnosis, race, gender, marital status, primary tumor site, tumor size, tumor grade, Tumor-Lymph Node-Metastasis (TNM) stage, surgical type, postoperative adjuvant therapy (POAT) record, the number of lymph nodes (LNs) examined, the number of positive LNs, survival time, and death classification were collected and dichotomized through the receiver operating characteristic (ROC) curve. The LNR was defined as the ratio of positive LNs to the total number of LNs examined. The Kaplan-Meier method and Cox regression models were used to assess the association between LNR vs. cancer-specific survival (CSS) and overall survival (OS). RESULTS: The 5-year CSS and OS rates of the 391 patients were 44% and 33.7%, respectively. The median LNR was 0.083 [interquartile range (IQR), 0.043–0.179], and the optimal cut-off value of LNR was 0.23. Kaplan-Meier curves showed that patients with LNR ≥0.23 had significantly shorter CSS and OS than LNR <0.23. In multivariable analysis, large tumor size [hazard ratio (HR): 1.012, P=0.016], N3 stage (HR: 2.113, P=0.040), M1 stage (HR: 2.458, P=0.041), with POAT (HR: 0.559, P=0.001), and LNR ≥0.23 (HR: 1.795, P=0.001) independently predicted CSS, while old age (HR: 1.019, P=0.009), large tumor size (HR: 1.012, P=0.006), M1 stage (HR: 3.422, P=0.001), with POAT (HR: 0.610, P=0.001), and LNR ≥0.23 (HR: 1.667, P=0.001) independently predicted OS. The subgroup analysis showed that patients with LNR ≥0.23 shared worse CSS and OS in either N2 or N3 subgroups than those with LNR <0.23. Furthermore, POAT provided an independent protective factor in the LNR ≥0.23 group, while it had no significant effect in the LNR <0.23 group. CONCLUSIONS: This study demonstrates a strong association between LNR and prognosis in patients with LNs metastatic HSCC. Further, it provides an alternative tool for providing supplemental information regarding prognosis.