Clinical Significance of Molecular Micrometastasis in the Sentinel Lymph Node of Early-stage Non–Small Cell Lung Cancer Patients

Objectives: Metastatic affectation of lymph node is the main prognostic factor in localized lung cancer. A pathologic study of the obtained samples, even after adequate lymphadenectomy, showed tumor relapses for 20% of stage I patients after oncological curative surgery. We evaluated the prognostic value of molecular micrometastasis in the sentinel lymph node of patients with early-stage lung cancer. Patients and Methods: The sentinel node was marked immediately after performing thoracotomy by peritumorally injecting 0.25 mCi of nanocoloid of albumin (Nanocol1) labeled with Tc-99m in 0.3 mL. Guided by a Navigator1 gammagraphic sensor, we proceeded to its resection. The RNA of the tissue was extracted, and the presence of genes CEACAM5, BPIFA1, and CK7 in mRNA was studied. The significant association between the presence of micrometastasis, clinicopathologic characteristics, and patients' outcome was assessed. Results: Eighty-nine stage I-II non–small cell lung cancer patients were included in the study. Of the 89 analyzed sentinel lymph nodes, 44 (49.4%) were positive for CK7, 24 (26.9%) for CEACAM5, and 17 (19.1%) for BPIFA1, whereas 10 (11.2%) were positive for the 3 analyzed genes. A survival analysis showed no significant relation between the presence of molecular micrometastasis in the sentinel node and patients' progression. Conclusions: The molecular analysis of the sentinel node in patients with early-stage lung cancer shows node affectation in cases staged as stage I/II by hematoxylin-eosin or an immunohistochemical analysis. However, this nodal affectation was not apparently related to patients' outcome.

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