National analysis of the incidence and prognostic importance of nodal metastases in atypical lung carcinoid tumors.

OBJECTIVE: To evaluate the relationship of atypical lung carcinoid (AC) tumor size, nodal involvement, and survival. METHODS: Patients recorded in the National Cancer Database who underwent lobectomy or sublobar resection for lung AC between 2006 and 2022 were included. A multivariable logistic regression model was used to identify independent factors associated with lymph node involvement. Survival was assessed using the Cox proportional hazard model and Kaplan-Meier method. RESULTS: A total of 1927 patients met the study's inclusion criteria. The incidence of overall node positivity was 33.4%. The incidence of positive pathologic nodes in patients who were clinically considered node-negative was 25.2%. Lymph node involvement was more likely with increasing tumor size, ranging from a rate of 19.1% in the subset of patients with subcentimeter-sized tumors to 45.9% with tumors larger than 7 cm. Increasing tumor size was associated with a higher risk of nodal involvement in a multivariable analysis. Positive nodes were associated with significantly worse survival in both Kaplan-Meier analysis (5-year survival, 71.7% vs 88.5%; P < .001) and multivariable analysis (hazard ratio, 1.77; 95% confidence interval, 1.41-2.23; P < .001). CONCLUSIONS: Nodal involvement is a critical factor associated with survival for AC tumors of the lung and occurs at a high rate, even when tumors are very small. Lymph node evaluation at the time of AC resection should be considered regardless of tumor size to most accurately stage patients.