Epidemiology and Prognosis of Lymphoepithelioma-like Carcinoma: a Comprehensive Analysis of Surveillance, Epidemiology, and End Results (SEER) Database

Aim: Lymphoepithelioma-like carcinoma (LELC) is a rare histological types of solid tumors. The present study aims to comprehensively describe the demographic and clinical features of LELC using surveillance, epidemiology, and end results (SEER) database, with an emphasis on the prognostic difference according to primary tumor sites of LELC.

Materials And Methods: A population cohort with histologically diagnosed LELC were identified from SEER database between 1973 and 2016. Age-adjusted incidence rates and cancer-specific survival (CSS) were determined. Cox-regression proportional hazards model was used for both univariate and multivariate analyses.

Results: In total, 2106 patients with LELC were identified, with the most common diagnosed primary tumor site of nasopharyngeal LELC (56.22%), followed by non-nasopharyngeal head and neck LELC (21.32%) and respiratory system (7.83%). The overall age-adjusted incidence of LELC was 0.091 per 100,000. The CSS rates of LELC patients at 5, 10, 15, and 20 years were 76%, 69%, 65%, and 61%, respectively. A tendency of decreasing incidence of LELC was observed in the past decade. Univariate analysis indicated that sex [hazard ratio (HR) 1.21, p = 0.031], year of diagnosis (HR 0.60 and 0.63, p < 0.001), race (HR 1.29, p = 0.0021), age (HR 1.25, p = 0.0072), summary tumor stage (HR 1.97, and 4.57, both p < 0.001), number of positive LN(HR2.21, p < 0.001), surgery (HR 0.58, p = 0.0033), chemotherapy (HR 1.19, p = 0.037) and primary tumor site (p < 0.001) were significant factors associated with prognosis of LELC. In multivariate analysis, age (HR 1.75, p = 0.03), distant stage (HR 6.57, p = 0.0001), number of positive LN (HR 2.63, p = 0.0015) and non-nasopharyngeal head and neck LELC (HR 0.37, p = 0.0031) were significantly independent predictors for CSS of LELC. In sub-group analysis, radiotherapy significantly improves CSS for nasopharyngeal LELC (HR 0.57, p = 0.0002), while surgery significantly improve CSS for non-nasopharyngeal LELC (HR 0.33, p < 0.0001).

Conclusion: Based on SEER data analysis, age older than 50 years, distant stage and more than three positive LN are significantly associated with worse CSS for LELC, while the prognosis of non-nasopharyngeal head and neck LELC is significantly better than nasopharyngeal LELC. Local treatments for LELC could be recommended according to primary tumor sites.