[Clinical characteristics and treatment strategies of nasopharyngeal carcinoma with concurrent thyroid cancer].

Objective: To analyze the clinical characteristics and treatment strategies of nasopharyngeal carcinoma (NPC) with concurrent thyroid cancer (TC). Methods: A case series study was carried out. The clinical data of NPC patients with concurrent TC diagnosed by pathology and with complete follow-up data who were initially treated in Sun Yat-sen University Cancer Center from January 2017 to December 2023 were retrospectively reviewed. Patients were divided into NPC-first treatment group and TC-first treatment group based on the treatment sequence. Clinical characteristics, treatment strategies and prognosis of patients were compared between the two groups. Results: A total of 53 cases (28 males and 25 females) aged [M (Q₁, Q₃)] 42 (34, 48) years were included. Sixteen (31.2%) patients underwent TC treatments first, while 37 patients (69.8%) underwent NPC treatments first. There were 64.2% (34/53) patients diagnosed based on NPC-specific ENT symptoms. The Epstein-Barr virus (EBV) DNA-negative rate [62.5% (10/16) vs 24.3% (9/37), P=0.008], the rate of double-lobe thyroid lesions based on positron emission tomography/computed tomography (PET/CT) scans (3/6 vs 1/26, P=0.015), the rate of cervical lymph node metastasis of TC based on ultrasound scans [31.2% (5/16) vs 5.4% (2/37), P=0.021] and the rate of stageⅠ-Ⅲ NPC [87.5% (14/16) vs 54.1% (20/37), P=0.020] were higher in patients who underwent TC treatment first compared with those who underwent NPC treatment first. The interval between NPC and TC treatments was longer in NPC-first treatment group than that of TC-first treatment group [166 (125, 281) days vs 74 (29, 90) days, P<0.001]. In patients who underwent TC treatment first, fewer level Ⅵ cervical lymph nodes were included in the clinical target volume (CTV) compared with those who underwent NPC treatment first [10.0% (2/20) vs 40.0% (16/40), P=0.017]. After 38.7 (18.3, 52.3) months of follow-up, there was no statistically significant difference in expected 3-year progression free survival rates and overall survival rates between the two groups (87.3% vs 83.6% and 100% vs 87.5%, respectively, both P>0.05). Conclusions: The majority of NPC patients with concurrent TC were initially diagnosed due to NPC-related symptoms, consequently leading to a higher proportion receiving NPC treatment as their primary therapy. For NPC patients with concurrent TC, receiving TC treatment first facilitates the guidance of CTV.