Postinduction positron emission tomography assessment of N2 nodes is not associated with ypN2 disease or overall survival in stage IIIA non-small cell lung cancer.

Objective: Induction therapy is often recommended for patients with clinical stage IIIA-N2 (cIIIA/pN2) lung cancer. We examined whether postinduction positron emission tomography (PET) scans were associated with ypN2 disease and survival of patients with cIIIA/pN2 disease. Methods: We performed a retrospective review of a prospectively maintained database to identify patients with cIIIA/pN2 non-small cell lung cancer treated with induction chemotherapy followed by surgery between January 2007 and December 2012. The primary aim was the association between postinduction PET avidity and ypN2 status; the secondary aims were overall survival, disease-free survival, and recurrence. Results: Persistent pathologic N2 disease was present in 61% of patients (61 out of 100). PET N2-negative disease increased from 7% (6 out of 92) before induction therapy to 47% (36 out of 77) afterward. The sensitivity, specificity, and accuracy of postinduction PET for identification of ypN2 disease were 59%, 55%, and 57%, respectively. Logistic regression analysis indicated that postinduction PET N2 status was not associated with ypN2 disease. Of the 39 patients with both pre- and postinduction PET N2-avidity, 25 (64%) had ypN2 disease. The 5-year overall survival was 40% for ypN2 disease versus 38% for N2-persistent disease (P =.936); the 5-year overall survival was 43% for postinduction PET N2-negative disease versus 39% for N2-avid disease (P =.251). The 5-year disease-free survival was 34% for ypN2-negative disease versus 9% for N2-persistent disease (P =.079). Conclusions: Postinduction PET avidity for N2 nodes is not associated with ypN2 disease, overall survival, or disease-free survival in patients undergoing induction chemotherapy for stage IIIA/pN2 disease.