Nasopharyngeal carcinoma survival by histology in endemic and non-endemic areas

Background To investigate the prognostic implications of histology among nasopharyngeal carcinoma (NPC) using the data from a Chinese cohort and the Surveillance, Epidemiology, and End Results (SEER) database.Methods We included patients diagnosed with WHO II and III subtypes NPC from two independent cohorts (Xiamen [XM]-NPC cohort and SEER-NPC cohort).Results We identified 726 patients in the XM-NPC cohort and 1334 patients in the SEER cohort. In the XM-NPC cohort, 94 (12.9%) and 632 (87.1%) patients had WHO II and III subtypes, respectively. In the SEER-NPC cohort, 839 (62.9%) and 495 (37.1%) patients had WHO II and III subtypes, respectively. WHO II subtype patients had a higher smoking rate than the WHO III subtype (57.4% vs. 43.4%) in the XM-NPC cohort. There were no significant differences in age, gender, tumor stage, or nodal stage between the two subtypes in both cohorts. In the XM-NPC cohort, patients with the WHO II subtype had worse locoregional relapse-free survival (82.2% vs. 89.5%, p = 0.063), distant metastasis-free survival (72.4% vs. 85.9%, p = 0.028), disease-free survival (61.6% vs. 78.8%, p = 0.003), and overall survival (OS) (71.7% vs. 84.0%, p = 0.035) than those with WHO III subtype. In the SEER-NPC cohort, patients with the WHO II subtype had worse NPC-specific survival (81.1% vs. 89.4%, p