Epidemiology of Unconventional Histological Subtypes of Urethral Cancer

INTRODUCTION: The aim of the study was to examine cancer-specific mortality (CSM) of unconventional urethral cancers. METHODS: Within the SEER (2004–2016) database, we analyzed CSM of 165 patients with unconventional urethral-cancer histology. Kaplan-Meier plots were used to test the effect of unconventional histologies in urethral cancer on CSM. RESULTS: Of 165 eligible patients, the Mullerian type accounted for 55 (33.3%) versus melanocytic (26.7%) versus neuroendocrine 25 (15.2%) versus lymphoma 22 (13.3%) versus mesenchymal/sarcoma 15 (9.1%) versus spindle cell 4 (2.1%) patients. Median age at diagnosis was 81 years in spindle cell, 75 in melanocytic, 74 in neuroendocrine and mesenchymal/sarcoma, 67 in lymphoma, and 62 years Mullerian type (p < 0.001). Of all, 116 (70.3%) were female. The Mullerian type exhibited the highest female ratio (96.4%) versus the lowest female ratio in neuroendocrine (24.0%). The Mullerian type was most frequent in African-American females. In Caucasian females, the melanocytic type was most frequent (49.1%). In African-American (38.9%) and Caucasian males (33.3%), neuroendocrine histology was most frequent. Three-year CSM was, respectively, 27.5%, 23.1% 22.3%, 20.5%, and 16.1% for melanocytic, mesenchymal/sarcoma, Mullerian type, neuroendocrine, and lymphoma histology. Median cancer-specific survival was 106 versus 10 months for combined nonmetastatic versus metastatic nonconventional histologies. CONCLUSION: Important age, sex, racial/ethnic group distribution, and survival differences exist between each unconventional urethral-cancer histological subtypes.