Stage IV Lung Cancer AJCC v9

**Semantic type:** Neoplastic Process

**Definition:** Stage IV includes: IVA: (Any T, Any N, M1a); (Any T, Any N, M1b); IVB: (Any T, Any N, M1c1); (Any T, Any N, M1c2). M1a: Metastasis in pleural or pericardial nodules, and/or malignant pleural or pericardial effusions, and/or separate tumor nodule(s) in a contralateral lobe. Note: Most pleural (pericardial) effusions with lung cancer are a result of the tumor. In a few patients, however, multiple microscopic examinations of pleural (pericardial) fluid are negative for tumor, and the fluid is non-bloody and not an exudate. If these elements and clinical judgment dictate that the effusion is not related to the tumor, the effusion should be excluded as a staging descriptor. M1b: Single extrathoracic metastasis in a single organ system (including involvement of a single non-regional node). M1c1: Multiple extrathoracic metastases in a single organ system. Note: For example, the skeleton is considered one organ. Several metastases in a single bone or several metastases in several bones are classified as M1c1. M1c2: Multiple extrathoracic metastases in multiple organ systems. (AJCC 9th ed.)