Recurrence and Emergence of New Primary Tumors in Patients with Resected Pathological Stage 1A Non–Small Cell Lung Cancer

Rationale: Lung cancer screening has made early-stage non–small cell lung cancer (NSCLC) more common and highly curable. However, evidence on post-treatment surveillance, new radiological findings, and distinguishing recurrence from new primary cancers remains limited. Objectives: Our study evaluated outcomes in patients with pathologic stage 0/1A first primary NSCLC after surgery, including overall survival and the classification of new findings as either recurrence or second primary tumors. We also explored potential improvements to current classification criteria. Methods: We analyzed 653 patients with pathologic stage 0/1A NSCLC from the IELCART cohort (2016–2023). Radiological findings were reviewed to classify lung cancer diagnoses as second primaries or recurrences using a five-step approach based on histopathology, genetics, timing, and multidisciplinary discussions. Survival was analyzed with Kaplan-Meier curves and log-rank tests. Results: Among 653 patients (61.1% women, median age 69 yr), 74 (11.3%) later had radiological findings confirmed as lung cancer, which was more frequent in men (15.7% vs. 8.5%), those with higher pack-years, and chronic obstructive pulmonary disease. New malignant events were most common in current smokers (19.1%), followed by former smokers (15.2%) and never smokers (1.6%). Of these, 30 (5%) were second primaries, and 44 (7%) were recurrences. Nonsolid cancers showed no recurrences. Recurrences peaked at 12–18 months, whereas second primaries occurred steadily at 0.6% annually. Overall survival differed significantly between patient groups (P < 0.0001), with overall survival of 58.2% with recurrences, 77.9% with new primaries, and 94.3% with no new cancer after a median follow-up of 3.5 years. Conclusion: Among 653 patients, 7% had recurrences, whereas new primaries (5%) became more frequent after 3 years, occurring steadily at 0.6% per year, with distinct survival outcomes. New malignant events were more common in men, smokers, and those with chronic obstructive pulmonary disease. Notably, all malignancies in nonsolid cancers were new primaries. These findings emphasize the need for tailored surveillance strategies.