The prognostic role of radiotherapy and radiotherapy target in cervical lymph node metastatic squamous cell carcinoma with unknown primary: a retrospective study

Objectives Aim to analyze the effect of radiotherapy for cervical lymph node metastatic carcinoma with unknown primary (CCUP) and compare the survival benefits between Comprehensive radiotherapy and Involved Field radiotherapy. Materials and methods The patients diagnosed with CCUP between 2009 and 2019 in our institution were analyzed retrospectively. The categorical variables were tested by chi(2) test. Kaplan-Meier method was used for survival analysis. Log-rank test and Cox proportional hazards regression were performed with overall survival (OS) and disease-free survival (DFS) as the primary outcome variables. Results Of 139 patients, 64.7% (90/139) of them received radiotherapy. Of the 90 patients who underwent radiotherapy, 45.6% (41/90) received Involved Field radiotherapy and the rest 49 patients received Comprehensive radiotherapy. The median follow-up of 139 patients is 69 months. The 1-year, 3-year, and 5-year OS rates are 87%, 62%, and 39%, respectively, and the DFS rates are 73%, 45%, and 29%, respectively. Multivariate analysis of 139 patients with CCUP shows that differentiation grade, N stage, radiotherapy, and the length of the largest lymph node (D-maxLN) are the independent prognostic factors for both OS and DFS. Subgroup analysis of 90 patients who received radiotherapy shows that the Comprehensive radiotherapy group has a better OS (P < 0.001) and DFS (P < 0.001) compared with Involved Field radiotherapy. Conclusion Radiotherapy is the independent prognostic factor for CCUP. Comprehensive radiotherapy may be superior to Involved Field radiotherapy in survival benefits.