The Prognostic Significance of the 8th Edition TNM Staging of Pulmonary Carcinoid Tumors: A Single Institution Study With Long-term Follow-up.

Pulmonary carcinoid tumors are an uncommon tumor in the lung, representing <1% to 2% of all primary lung cancers, and have a relatively indolent clinical course. Because of their low incidence, these tumors do not have a specific staging system. However, since the 7th edition, the TNM Classification for Lung Cancer has been used in these tumors, though the ability of this staging classification to predict prognosis in carcinoid tumors is not well-studied. We report the largest single institution study of typical and atypical carcinoid tumors with recurrence as a measure of outcome and compared the ability of the 7th and 8th TNM Classification of Lung Cancer to predict recurrence in typical and atypical carcinoid tumors of the lung. All surgical lung resection cases from 1995 to 2016 with a diagnosis of primary lung carcinoid tumor were reviewed and clinicopathologic parameters, including tumor size, nodal status, histology (mitotic counts), and recurrence were recorded. The final cohort consists of 205 carcinoid tumors: 188 (92%) typical carcinoids and 17 (8%) atypical carcinoids. Pulmonary carcinoid tumors have an excellent prognosis with a low recurrence rate of 8%. Atypical carcinoids were significantly more likely to recur (median time to recurrence: 3 y) compared with typical carcinoids. By placing more emphasis on tumor size and nodal status in the staging classification, the TNM 8th edition was superior in predicting outcome compared with the TNM 7th edition.