During the past years, numerous investigators have been endeavoring to establish a standard terminology that would accurately describe the extent of a cancer. One such staging system for lung cancer has been formulated by the Task Force on Lung Cancer of the American Joint Committee for Cancer Staging and End-Results Reporting (AJCF). The AJC staging system employs the T-N-M nomenclature . In this system, the letter T represents the primary tumor N regional node involvement, M.

T. Numerical Suffix Assignment
The criteria are:
N Numerical Suffix Assignment
The first station lymph nodes are the intrapulmonary, peribronchial and hilar lymph nodes, which are contained within the visceral reflections. Second station lymph nodes are those in the mediastinum and may be paraesophageal, subcarinal, paratracheal, aortic or retrotracheal. Involvement of scalene, contra-lateral or extra-thoracic nodes is considered distant metastasis.
M Suffix Assignment
The metastatic status is signified by the letter "M" with subscripts O or 1 to indicate absence or presence of metastatic disease. "M1" signifies presence of metastasis in one or more distant organs. The common metastatic sites are Brain, Bone, Liver, Adrenal glands and subcutaneous tissue.
Group Staging
T, N and M combinations are used to group stage lung cancer. The staging is important in planning therapy and for estimating prognosis.