Impact of superior mediastinal metastasis on the prognosis of papillary thyroid carcinoma

The impact of lymph node (LN) metastasis on survival or tumor recurrence in patients with papillary thyroid carcinoma (PTC) is controversial. The objective of this study was to investigate the effect of superior mediastinal metastasis on the prognosis of patients with PTC and to identify any correlations between such metastasis and clinical indicators. Medical records of PTC patients who underwent surgery as their initial treatment between 1981 and 2008 at our institution were retrospectively reviewed. Patients with or without superior mediastinal metastasis were selected. Prognosis was determined using the Kaplan-Meier method and Cox-hazard regression model with the forward stepwise method. Correlations between multiple factors and superior mediastinal metastasis were investigated using a binary logistic regression analysis. The study cohort included 488 patients of whom 75 (15.4%) had superior mediastinal metastasis. The survival differences between patients with superior mediastinal metastasis dissected via the transcervical approach and patients without metastasis were not significant. The prognosis of patients with superior mediastinal metastasis dissected by sternotomy was significantly poorer. As for disease-free survival, significant differences were found between patients with superior mediastinal metastases dissected by either method and patients without metastases. The main variables predicting superior mediastinal metastasis were an age of 45 years or older and the total number of cervical LN metastases. Superior mediastinal metastasis was an independent predictive factor for recurrence-free survival in PTC patients. The main variables predicting superior mediastinal metastasis were being 45 years of age or older, and having a greater total number of cervical LN metastases.