Can lymph node next-generation sequencing assist in better predicting the prognosis of lung adenocarcinoma?

e15063 Background: Despite TNM staging, early-staged lung cancer patients are not exempt from the risks of recurrence or lymphatic spread. Next-generation sequencing (NGS) offers enhanced sensitivity in detecting tumor residues that may be undetected by traditional pathology. Methods: We retrospectively analyzed five lung adenocarcinoma patients who underwent surgery and later experienced recurrence. Lymph node samples were evaluated using immunohistochemistry (IHC) and NGS with a 437-gene cancer panel, categorizing samples by thoracic lymph node stations. Results: Five lymph node samples were IHC-positive, while seven were NGS-positive, with discrepancies in two cases. Notably, IHC-negative samples from patients P2 and P3 revealed mutations via NGS. Three patients developed lymph node metastasis, while two had brain metastases. Staging for P3 changed from N1 to N2a based on NGS results, indicating a worse prognosis. Patients with NGS-assessed N2 status experienced significantly shorter disease-free survival compared to N0 patients. Conclusions: NGS might enhance the detection of micrometastases in lymph nodes, improving disease staging, but further validation is warranted. Samples and test result from IHC and NGS. Patients P1 P2 P3 P4 P5 Samples (tumor/ lymph gland) tumor NO.5/6/7/9L NO.10/11L tumor NO.4L NO.7L NO.11/12L tumor NO.7L NO.10L NO.11L tumor NO.5,7/9L NO.10/11L tumor NO.2/4/7/8L NO.10/12L Pathological result negative negative No. 4 positive negative No. 11 and No. 12 positive negative negative No. 11 positive negative negative No.8 positive No.10 positive NGS result negative negative positive positive positive positive negative positive negative negative positive positive Number of mutations 40 0 0 23 11 2 24 4 1 0 4 34 0 0 9 1 5 Pathological-TNM T2aN0M0 T1bN2aM0 T2aN1M0 T2