Surgical indications for upper mediastinal dissection by sternotomy in patients with papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is a relatively indolent disease, despite the high incidence of lymph node metastases. Although less frequent, some upper mediastinal metastases of PTC cannot be removed without sternal resection. In this study, we investigated the prognostic impact of upper mediastinal dissection (UMD) by sternotomy on patients with mediastinal metastases of PTC. Charts of patients with PTC who underwent surgical treatment at our institution between 2006 and 2018 were retrospectively reviewed. Fifty-eight patients with upper mediastinal metastases were enrolled. Kaplan-Meier survival curves were compared, and Cox hazard regression models were used for analyses. Of the 58 patients with mediastinal metastasis, 12 (20.7%) underwent dissection of the prevascular nodes, 51 (87.9%) underwent dissection of the upper paratracheal nodes, and 14 (24.1%) underwent dissection of the lower paratracheal node. The preferred site of mediastinal metastasis was the upper paratracheal nodes. The 5 and 10-year disease-specific survival rates for patients after UMD were 74.6% and 58.7%, respectively. Among 25 patients (43.1%) with locoregional recurrence, 12 (20.7%) had mediastinal recurrence and 7 were eligible for additional UMD. Although distant metastasis was the predominant poor prognostic factor, mediastinal recurrences were more frequently unresectable than cervical recurrences, suggesting that mediastinal recurrence is a poor prognostic factor. Mediastinal metastases larger than 30 mm or metastases to the lower paratracheal nodes are considered a risk factor for mediastinal recurrence. UMD by sternotomy for patient with upper mediastinal metastases which are difficult to resect via transcervical approach is an effective treatment option to improve patient prognosis.