Recurrence Rates and Patterns after Radical Resection of Lung Carcinoids.

Atypical lung carcinoid (AC) is widely accepted to recur more often after radical resection than typical lung carcinoid (TC). However, their recurrence rates have never been compared in a multi-state competing risks model. We retrospectively reviewed files from patients with AC and TC who had been radically resected at our European Neuroendocrine Tumor Society Center of Excellence between 2009 and 2020. We estimated the recurrence rates between the AC and TC patients counting unrelated death as a competing event using Aalen-Johansen estimates and compared them using a multi-state Cox model. Finally, we analyzed all AC and TC recurrences as to resection type, pathological stage, resection margin, recurrence site, and time to recurrence. The study included 217 patients, of whom 194 had TC and 23 had AC. The median follow-up was 9.4 years. The AC patients experienced recurrence at a higher rate (hazard ratio [HR] 16.0, 95% confidence interval [CI] 5.3-47.9, < 0.001). Correspondingly, the 5- and 10-year recurrence rates were 18% and 32% for AC and merely 1.0% and 2.4% for TC. In patients without nodal involvement, AC recurred at a considerably higher rate (HR 41.2, 95% CI 8.7-194.8, < 0.001) than TC. In both AC and TC, most recurrences were distant and occurred in patients with a resection margin less than 2 cm. We conclude that AC recurs more often than TC, even in patients without nodal involvement at surgery, suggesting that all AC patients regardless of their pathological stage should undergo close follow-up care after surgery.