Refining the TNM M1 Subcategory for De Novo Metastatic Nasopharyngeal Carcinoma

Abstract

To refine oligometastatic disease (OMD) and construct M1 categories for de novo metastatic nasopharyngeal carcinoma (dmNPC) MATERIALS/METHODS: We included 504 patients who received chemotherapy and/or radiotherapy between 2010-2019 from two centers (training and validation cohort). Multivariable analyses were used to evaluate the prognostic value of OMD and metastatic organs, which were then used to construct M1 categories RESULTS: The median follow-up for the training and validation cohorts were 46 and 57 months, respectively. OMD (≤ 2 metastatic organs and ≤ 5 metastatic lesions) had the highest C-index compared to the other models in both cohorts. Multivariable analyses, in which both OMD and liver metastases did not coexist, revealed that OMD (hazard ratio [HR] = 2.110 and 1.598) and liver metastases (HR = 1.572 and 1.452) were prognostic factors for overall survival (OS) in both cohorts. Based on OMD and liver metastases, patients with dmNPC were divided into M1a (OMD without liver metastases) and M1b (OMD with liver metastases or polymetastatic disease). The 3-year OS of the M1a patients was better than that of the M1b patients in both cohorts (both p < 0.001). In the anti-PD1 mAb and chemotherapy cohorts, patients with M1ahad a significantly better median progression-free survival than those with M1b (p < 0.001) CONCLUSION: OMD with ≤ 2 metastatic organs and ≤ 5 metastatic lesions is an appropriate definition for dmNPC. M1 subcategories constructed based on OMD and liver metastases improved prognostic evaluation for patients with dmNPC who received chemotherapy or antiPD1 mAb treatment.