Clinical outcomes of a cohort of 271 patients with lung metastases from differentiated thyroid carcinoma

Context: Lung is the most common site of distant metastases from differentiated thyroid carcinoma (DTC). Objective: To investigate the outcomes of a cohort of patients with DTC and lung metastases (LM). Methods: A retrospective analysis of a cohort of 271 patients with LM was performed. Results: The female-to-male ratio was 1:1 and the median follow-up time was 5.9 (1.1–38.4) years. Papillary thyroid carcinoma (PTC) was the most frequent type (83.4%), mainly the classic variant, followed by follicular thyroid carcinoma (FTC, 10.3%) and Hürthle cell carcinoma (HTC, 6.3%). The prevalence of PTC, FTC and HCC was different between the micronodular and macronodular LM groups [87.4%, 6.3% and 6.3% vs. 74.6%, 19.0% and 6.3%, respectively (p =.013)]. Only 5.0% of the patients had LM diagnosed after a period of remission. LM were submitted to radioactive iodine treatment (RAIT) in 84.5% (52.8% showed ¹³¹iodine avid metastases). Complete remission was only achieved in 12.2%. Micronodular disease and age <55 years at LM diagnosis were associated with a better prognosis (p <.05). We found no difference in survival between patients with LM treated or not with RAIT. However, in patients submitted to RAIT, there was a tendency for longer survival in the group of patients with ¹³¹I avid lesions. Conclusion: The classic variant of PTC was the most frequent histology found in LM of DTC. LM are rarely diagnosed in the follow-up when complete remission is achieved after surgery and ¹³¹I. Younger age at LM diagnosis and a micronodular pattern are associated with a better prognosis.