Management of Retropharyngeal Lymph Node Metastases in Differentiated Thyroid Carcinoma.

BACKGROUND Retropharyngeal lymph node metastases (RPMs) from differentiated thyroid carcinoma (DTC) are rare. Treatment includes surgical resection, radioactive iodine (RAI) therapy, or external beam radiotherapy (EBRT). The objective of this study was to describe our experience in the management of DTC-associated RPMs. METHODS Patients diagnosed with a DTC-associated RPM from 1999 to 2018 were identified at our institution, using key search terms in imaging and histology reports. Patient and tumor characteristics were recorded, and patients were grouped according to RPM management: observation, nonsurgical treatment, or surgical resection. The estimated rates of local RPM control, disease-specific survival (DSS), and distant recurrence-free survival (DRFS) were calculated using the Kaplan-Meier method. RESULTS Of the 65 patients identified, 53 (82%) had RPM as a manifestation of recurrent disease. Twenty-five patients (38%) underwent observation, 13 (20%) received nonsurgical treatment (RAI, EBRT, and/or systemic therapy), and 27 (42%) underwent surgical resection. In the observation cohort, all patients had a stable RPM, which in the majority (80%) of cases remained <1.5 cm during the period of observation (median 28 months). Of the 13 patients in the nonsurgical treatment cohort, 3 received RAI therapy, 7 received EBRT, and 3 received systemic therapy only. In the surgical cohort, the median RPM maximum diameter was 2.0 cm (range 0.8-4.2 cm). The size of the RPM was predictive of surgical resection versus observation (p <0.001). A transcervical approach was employed in 19 patients, and a transoral approach in 8. The 5-year rate of local RPM control was 92%. For the whole cohort, the 5- and 10-year DRFS were 72% and 62%, respectively; the 5- and 10-year DSS were 93% and 81%, respectively. CONCLUSIONS DTC-associated RPM manifests as recurrent disease in the majority of patients. Select patients with a small-volume and nonprogressive RPM may be suitable for observation whereas surgery is likely warranted in large or progressing RPMs. In general, the presence of a RPM from DTC appears to be associated with aggressive disease.