American Board of Internal Medicine (ABIM) Certification Practice Exam

In the staging of non-small cell lung cancer, what indicates regional lymph node involvement?

1. Stage I

2. Stage II

3. Stage III

4. Stage IV

The correct answer is: Stage III

In the staging of non-small cell lung cancer (NSCLC), the classification system is generally based on the TNM system, which assesses the size and extent of the primary tumor (T), the involvement of regional lymph nodes (N), and the presence of distant metastasis (M). Regional lymph node involvement is specifically categorized as N1, N2, or N3, indicating various levels of nodal involvement. Stage I indicates localized disease without regional lymph node involvement, as the tumor is confined to the lung. Stage II marks a slight progression with potential involvement of local lymph nodes but typically denotes limited regional spread. Stage III signifies more extensive disease with significant regional lymph node involvement, showcasing that cancer has spread beyond the primary tumor site into nearby lymphatics. Stage IV indicates advanced disease with distant metastasis, representing a farther progression rather than involving just regional lymph nodes. Therefore, Stage III is the correct choice as it indicates that the cancer has spread to regional lymph nodes and reflects a more serious and advanced disease stage. This staging is critical for guiding treatment decisions and assessing prognosis in patients with NSCLC.