American Board of Internal Medicine (ABIM) Certification Practice Exam

What stage of lung cancer involves metastatic disease or malignant pleural effusion?

1. Stage I

2. Stage II

3. Stage III

4. Stage IV

The correct answer is: Stage IV

The stage of lung cancer that involves metastatic disease or malignant pleural effusion is Stage IV. At this advanced stage, the cancer has spread beyond the lungs to distant sites or has resulted in pleural effusion that is associated with malignancy. This may include metastasis to organs such as the liver, bones, or brain, reflecting the aggressive nature of the disease. In the earlier stages of lung cancer, such as Stage I, II, or III, the cancer may be more localized, either confined to the lungs or limited regional lymph nodes. Stage I includes tumors that are typically small and have not yet spread; Stage II may involve larger tumors or those that have spread to nearby lymph nodes but not to distant areas; Stage III indicates more extensive regional spread and significant lymph node involvement but does not encompass the widespread metastatic disease characteristic of Stage IV. Therefore, the defining factors of Stage IV—namely the presence of metastasis or malignant pleural effusion—correctly identify it as the stage where cancer has progressed significantly, indicating a poorer prognosis and more complex treatment considerations.