Effects of locoregional radiotherapy in de novo metastatic nasopharyngeal carcinoma: A real-world study.

BACKGROUND To evaluate the value of locoregional radiotherapy (LRRT) in de novo metastatic nasopharyngeal carcinoma (dmNPC) and identify predictive factors for additional LRRT after palliative chemotherapy (PCT). METHODS Overall survival (OS) was the primary endpoint. Patients who underwent PCT and LRRT were categorized as the PCT+LRRT group; patients who only received palliative chemotherapy were categorized as the PCT group. Oligometastatic diseases (OMD) was defined as ≤5 metastatic lesions and ≤2 metastatic organs. RESULTS A total of 168 patients were included for this study. The median OS of patients in the PCT+LRRT group was significantly higher than those in the PCT group (57 months vs. 22 months, P<0.001). Multivariate analyses (MVA) showed that LRRT (HR=0.533, 95% CI: 0.319-0.889, P = 0.016) and OMD (HR=0.548, 95% CI: 0.331-0.907, P = 0.019) were independent prognostic factors for dmNPC. Furthermore, Kaplan-Meier analyses showed that the 3-year OS of patients who received LRRT was significantly better than those who did not receive LRRT in the OMD subgroup (66.3% vs. 25.2%, P<0.001). While, the 3-year OS of patients who received LRRT and without LRRT was no different in the polymetastatic disease (PMD) subgroup (38.9% vs.11.5%, P = 0.115). MVA showed that LRRT was a favorable prognosticator in the OMD subgroup (HR=0.308, 95% CI: 0.159-0.598; P<0.001), and not a favorable prognosticator in the PMD subgroup (HR=0.510, 95% CI: 0.256-1.014, P = 0.055). CONCLUSIONS LRRT has the potential to prolong OS in NPC patients with de novo OMD. These results suggest that OMD is a potential indicator for filtering beneficiaries from LRRT.