Purpose: To determine the M1 sub-staging in synchronous metastatic nasopharyngeal carcinoma (smNPC) and to examine the effect of nasopharyngeal-neck radiotherapy (RT) and local treatment of metastases on overall survival (OS) of smNPC patients.
Patients and Methods: A total of 150 patients with smNPC were included. Metastatic characteristics associated with their potential prognostic significance were analyzed. Then, a stratification system of the M1 sub-staging in smNPC was provided according to metastatic features. Moreover, the OS of patients with or without nasopharyngeal-neck RT was compared by Log rank test. The OS of patients who received or did not receive local treatment of metastases was also analyzed.
Results: We successfully divided the M1 stage into three sub-staging: M1a (a single site with a single lesion), M1b (a single site with multiple lesions), and M1c (multiple sites with multiple lesions). The median OS was 53.2, 25.8, and 18.9 months for M1a, M1b, and M1c, respectively (p < 0.001). Nasopharyngeal-neck RT plus systematic chemotherapy (CT) significantly improved OS compared to systematic CT (median OS, 34.0 vs 15.2 months, p = 0.002). However, incorporation of local treatment of metastases did not bring survival benefit to smNPC patients who received nasopharyngeal-neck RT plus systematic CT (median OS, 25.8 vs 35.1 months, p = 0.374).
Conclusion: The sub-staging of the M1 stage in smNPC had promising prognostic value. Adding nasopharyngeal-neck RT on the basis of systematic CT markedly improved the survival of smNPC patients, while addition of local treatment of metastases to nasopharyngeal-neck RT plus systematic CT for smNPC needed further exploration.
Keywords: nasopharyngeal carcinoma, chemotherapy, local therapy, immunotherapy, metastasis