Abstract
IntroductionThe current metastatic category (M) of nasopharyngeal carcinoma (NPC) is a “catch-all” classification, covering a heterogeneous group of tumors ranging from potentially curable to incurable. The aim of this study was to design an M categorization system that could be applied in planning the treatment of NPC with synchronous metastasis.MethodsA total of 505 NPC patients diagnosed with synchronous metastasis at Sun Yat-sen University Cancer Center between 2000 and 2009 were involved. The associations of clinical variables, metastatic features, and a proposed M categorization system with overall survival (OS) were determined by using Cox regression model.ResultsMultivariate analysis showed that Union for International Cancer Control (UICC) N category (N1–3/N0), number of metastatic lesions (multiple/single), liver involvement (yes/no), radiotherapy to primary tumor (yes/no), and cycles of chemotherapy (>4/≤4) were independent prognostic factors for OS. We defined the following subcategories based on liver involvement and the number of metastatic lesions: M1a, single lesion confined to an isolated organ or location except the liver; M1b, single lesion in the liver and/or multiple lesions in any organs or locations except the liver; and M1c, multiple lesions in the liver. Of the 505 cases, 74 (14.7%) were classified as M1a, 296 (58.6%) as M1b, 134 (26.5%) as M1c, and 1 was not specified. The three M1 subcategories showed significant difference in OS [M1b vs. M1a, hazard ratio (HR) = 1.69, 95% confidence interval (CI) = 1.16–2.48, P = 0.007; M1c vs. M1a, HR = 2.64, 95% CI = 1.75–3.98, P < 0.001].ConclusionsWe developed an M categorization system based on the independent factors related to the prognosis of patients with metastatic NPC. This system may be helpful to further optimize individualized care for NPC patients.
Highlights
The current metastatic category (M) of nasopharyngeal carcinoma (NPC) is a “catch-all” classification, covering a heterogeneous group of tumors ranging from potentially curable to incurable
The most frequently involved locations for metastases were the bones (65.9%), the liver (30.7%), distant lymph nodes (28.5%), and the lungs (26.9%); isolated organ metastasis was common among the bone (65.9%), the lung (41.2%), and the liver (36.1%); and the metastasis was rare in distant lymph nodes (6.9%)
Our study provided several notable findings: (1) among 505 NPC patients with synchronous metastasis, the most frequently involved organs or sites at diagnosis were the bones (65.9%), the liver (30.7%), distant lymph nodes (28.5%), and the lungs (26.9%), respectively; (2) Union for International Cancer Control (UICC) N category, number of metastatic lesions, liver involvement, cycles of chemotherapy, and radiotherapy to primary tumors were independently associated with the overall survival (OS) of patients with synchronous metastatic NPC; and (3) based on liver involvement and number of metastatic lesions, we proposed a new M categorization system to further subdivide the population into three M1 subcategories, which showed a high degree of difference regarding OS and have important implications in the management of the metastatic disease
Summary
The current metastatic category (M) of nasopharyngeal carcinoma (NPC) is a “catch-all” classification, covering a heterogeneous group of tumors ranging from potentially curable to incurable. There is emerging evidence that the anatomic extent of metastasis closely associates with the prognosis of patients with metastatic NPC. A growing body of evidence showed that long-term survival could be achieved for selective NPC patients with limited metastatic lesions by a combination of systemic and local therapies [17, 18]. These findings suggest that further subdivision of the M category for metastatic NPC may be necessary to aid clinicians in assessing the prognosis and planning the treatment. Because NPC patients with synchronous metastasis underwent different treatment regimens and had different survival rates versus those with metachronous metastasis [12, 19], a detailed analysis of the data of metastatic NPC based on a large cohort of patients with synchronous metastasis is warranted
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