TNM staging of lung cancer: T refers to the tumor; N refers to lymph node metastasis; and M refers to the presence or absence of distant metastasis.
T is subdivided into seven categories: Tx, T0, Tis, T1, T2, T3, and T4: Tx, meaning that the primary tumor cannot be evaluated, or cancer cells are found in sputum or bronchial washings, but no tumor is seen on imaging or bronchoscopy. t0, no evidence of a primary tumor. tis, carcinoma in situ. t1, tumor with a maximum diameter less than or equal to 3 cm. T2, tumor with maximum diameter greater than 3 cm, but less than or equal to 7 cm, or accumulation to the main bronchus. However, the tumor is located greater than or equal to 2 cm from the ramus, or involves the dirty pleura, or extends to the hilum with atelectasis or obstructive pneumonia, but does not involve the whole lung. T3, the tumor has a maximum diameter greater than 7 cm, or any size tumor has directly invaded the chest wall, diaphragm, phrenic nerve, mediastinal pleura, or pericardium. T4, tumor of any size has directly invaded the mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, and ramus, invasion of any of the above would be considered in this period, and single or multiple satellite nodules in the same lobe as the primary tumor. The nodule is a single or multiple nodules appearing in the other lobe of the lung.
N is subdivided into five types: Nx, regional lymph nodes cannot be evaluated. n0, no regional lymph node metastasis. n1, ipsilateral peribronchial lymph nodes and, or ipsilateral hilar lymph nodes and intrapulmonary lymph node metastasis, including direct invasion of the primary tumor. n2, ipsilateral mediastinal and, or subrhinal lymph node metastasis. n3, contralateral mediastinal and, or subrhinal lymph nodes. contralateral hilar lymph nodes, and ipsilateral or contralateral oblique or supraclavicular lymph node metastases.
M is subdivided into M0 and M1: M0, meaning no distant metastases; M1, meaning distant metastases are present.