Prognostic impact of immunohistopathologic features in definitive radiation therapy for nasopharyngeal cancer patients

Our previous study by Murakami N, Mori T, Nakamura S, Yoshimoto S, Honma Y, Ueno T, Kobayashi K, Kashihara T, Takahashi K, Inaba K, Okuma K, Igaki H, Nakayama Y, Itami J. (J Radiat Res. 2019 Jul 30. pii: rrz053. doi: 10.1093/jrr/rrz053. [Epub ahead of print]) showed that strong expression of epithelial cell adhesion molecule (EpCAM) was associated with radiation resistance in head and neck squamous cell cancer patients (SCC). In this study, the prognostic impact of histopathologic features including EpCAM for nasopharyngeal cancer (NPC) patients was investigated. Since 2009, our institution has performed chemoradiation for locally advanced NPC patients with intensity modulated radiation therapy (IMRT). Tri-weekly adjuvant cisplatin (CDDP, 80 mg/m(2)) was administered concurrently with definitive radiation therapy 70 Gy in 35 fractions. One month after radiation therapy, adjuvant chemotherapy of three cycles of CDDP/5 fluorouracil (5-FU) was administered. Using a pretreatment biopsy specimen, EBV-encoded small RNA in situ hybridization (EBER-ISH), EpCAM, p16 and p53 were assessed by immunohistochemical analysis. Between May 2009 and September 2017, 51 NPC patients received definitive radiation therapy. Five, 13, 17 and 16 patients were staged as I, II, III and IV, respectively. The median follow-up period for alive patients was 31.1 months (12.4–109.7 months). Three-year overall survival (OS), progression-free survival (PFS) and locoregional control (LRC) were 87.1, 57.1 and 85.7%, respectively. EpCAM, p16 and p53 were not associated with PFS, OS nor LRC. Three-year PFS for patients with keratinizing and non-keratinizing SCC were 25 and 60.5%, respectively (P = 0.033, hazard ratio 4.851 (95% confidence interval 1.321–17.814)).Prognosis of NPC patients with keratinizing SCC was worse than non-keratinizing SCC patients, suggesting a biological difference between the two types of tumor.