Patients with head and neck cancer are at high risk of developing additional second primary tumors in the aerodigestive tract as a result of the field cancerization phenomenon. In this context, the appearance of a new neoplasm often poses a problem in differential diagnosis between recurrence and new primary tumor. Twelve patients with nasopharyngeal carcinoma (NPC) who received radiation therapy for the primary tumor and developed a second epithelial malignancy in the nasal cavity or nasopharynx during the follow-up period are presented in this report. The differentiation between the 2 entities based on the spatiotemporal relations, histological features, and the status of Epstein-Barr virus in tumor lesions are also presented. Our study showed that the epithelial malignancy after NPC having late-onset or prolonged interval (range, 5 to 18 years), different histological patterns (keratinizing squamous cell carcinoma, neuroendocrine carcinoma, or small cell carcinoma) distinct from the primary NPC (differentiated or undifferentiated nonkeratinizing carcinoma), and absence of Epstein-Barr virus, indicate a newly developed tumor rather than recurrent NPC. Our observations showed for the first time that second primary epithelial malignancy developed in the nasal cavity or nasopharynx years after curative therapy for NPC with a prevalence of 0.4% (12/2,794). Wild-type p53 protein was expressed more often in the original NPC (9 of 12) than in the second tumors (4 of 10), but the significance was not statistically significant (P = .2048). Genomic analysis for p53 mutation and in situ hybridization for human papillomavirus showed negative results, indicating that both important molecular events in NPC or head and neck cancer play a small role in this particular type of newly developed second malignant tumor. More studies are warranted for further clarification for the development of second epithelial malignancies in treated NPC patients. (C) 2000 W.B. Saunders Company.
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