Histological subtype is the most important determinant of survival in metastatic papillary thyroid cancer

We aimed to identify prognostic histopathological and clinical factors that modify survival in metastatic PTC. All cases of metastatic PTC treated at our department in the last 20 years were reviewed and analyzed.Histological subtype was the most important determinant of survival, as classic PTC demonstrated clearly improved survival compared to follicular subtype of PTC and other less frequently seen histological subtypes. The instant risk of death for the other histological subtypes was 4.56 times higher than the risk for the classic papillary type. Overall, a 10-year survival of 76.6% in our patients was seen.Patients with aggressive variants of PTC are more at risk for the development of metastatic disease. In these patients, established treatment modalities (surgery, radioiodine therapy) should be offered promptly, as well as close follow-up.Differentiated thyroid cancer, comprising papillary and follicular thyroid cancer, generally carries a good prognosis. Papillary thyroid cancer (PTC) is the most frequent type of thyroid malignancy and its metastases are usually lymphatic [1]. The risk of distant metastases, usually to the lung, mediastinal lymph nodes and bone, is greater in follicular than in papillary carcinoma [2]. Distant metastases from PTC may occur with a frequency ranging from 1.73-8.4% in most studies [3,4]. The most common site of distant metastases from PTC is the lung followed by mediastinal lymph nodes [5]. Less often, distant metastases may appear in bones [6], central nervous system [7,8], liver [9], pericardium and pleura [10], kidney [11], pancreas [12], skin and muscle [13], gastrointestinal tract [14]. As effective treatment may not exist for many of these patients, it is of paramount importance to identify, if possible, those who are at greater risk for developing metastatic disease.A limited number of retrospective studies have analyzed the prognostic factors, which affect clinical outcome in metastatic PTC. Prognostic factors as sex a