Diagnostic yield of routine frozen section pathology examination of lymph nodes in lung resections for clinical stage IA NSCLC.

Objective: Intraoperative identification of lymph node involvement by carcinoma has an impact on the surgical treatment of patients with clinical stage IA NSCLC. This study aimed to identify the diagnostic performance of routine intraoperative frozen section pathology (FSP) evaluation of lymph nodes in these patients.

Methods: Patients with clinical stage IA NSCLC who underwent curative-intent lung resections during 2018-2023 were included. Pathology reports were retrospectively reviewed for data on lymph node evaluation and findings from FSP and final pathology. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for the detection of node-positive disease.

Results: Of 1008 patients who had surgery during the study period, 909 (90.2%) were included in this analysis. Nodal upstaging occurred in 46 (5.1%) patients, corresponding to pN1 in 31 (3.4%) and pN2 in 15 (1.7%). FSP detected patients with node-positive disease with a sensitivity of 80.4%, specificity of 99.9%, PPV of 97.4%, and NPV of 99.0%. Of 7016 lymph nodes, 95 (1.4%) were involved by carcinoma on final pathology. At the lymph node level, FSP detected nodal disease with a sensitivity of 83.2%, specificity of 100%, PPV of 98.8%, and NPV of 99.8%. Of 565 patient with a plan to undergo sublobar resection, 556 (98.4%) had all negative lymph nodes on FSP; only 5 (0.9%) were found to have node-positive disease on final pathology.

Conclusions: FSP performs well detecting lymph node metastasis intraoperatively in patients with clinical stage IA NSCLC. FSP use should be considered as sublobar resections gain widespread application.