Survival Effects of Radiotherapy on Patients Newly Diagnosed with Distant Metastatic Nasopharyngeal Carcinoma in Non-High-Incidence Areas

Purpose: To analyze the effects of radiotherapy and its timing on the survival and safety of patients with newly diagnosed distant metastatic NPC in non-high-incidence areas. Patients and Methods: We retrospectively analyzed 94 newly diagnosed NPC patients with distant metastatic admitted to our hospital from January 2011 to June 2018. They were divided into three groups: no radiotherapy group received chemotherapy alone, early radiotherapy group was combined with radiotherapy during 1 to 3 cycles of chemotherapy, and late radiotherapy group was combined with radiotherapy after 4– 6 cycles of chemotherapy were effective. The efficacy and side effects of the three groups were compared, and the prognostic factors were analyzed. Results: The 6-month, 1-year and 2-year PFS were 53.6%, 14.3% and 3.6% in no radiotherapy group, 71.0%, 38.7% and 19.4% in early radiotherapy group, 88.6%, 48.6% and 22.9% in late radiotherapy group; the radiotherapy groups were better than the no radiotherapy group, and the difference was statistically significant ( P < 0.017). The 1-year, 2-year and 3-year OS were 75.0%, 32.1% and 0 in no radiotherapy group, 77.4%, 54.8% and 12.9% in early radiotherapy group, 85.7%, 71.4% and 31.4% in late radiotherapy group; the radiotherapy groups were better than the no radiotherapy group, and the differences were statistically significant ( P < 0.017). There was no significant difference in OS and PFS between the two radiotherapy groups. Univariate and multivariate analysis showed that HBV ( P = 0.031), number of metastases ( P = 0.002), liver metastases ( P = 0.038), radiotherapy ( P < 0.001) and treatment response ( P = 0.011) were related to OS. There was no significant difference in the incidence of adverse events ( P > 0.017). Conclusion: Early and late combined radiotherapy had similar clinical efficacy and both prolonged PFS and OS for patients with newly diagnosed distant metastatic NPC in non-high-risk areas. If chemotherapy response is expected to be poor, radiotherapy can be received early. Keywords: radiotherapy, nasopharyngeal carcinoma, metastasis, non-high-incidence area, prognosis