STAGING OF LUNG CANCER -NSCLC

The Revised International System for Staging Lung Cancer

The Revised International System for Staging Lung Cancer, based on information from a clinical database of more than 5,000 patients, was adopted in 2010 by the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer.[18,19] These revisions provide greater prognostic specificity for patient groups; however, the correlation between stage and prognosis predates the widespread availability of PET imaging.
Summary of Changes
This staging system is now recommended for the classification of both NSCLC and small cell lung carcinomas and for carcinoid tumors of the lung.[19]
The T (primary tumor) classifications have been redefined as follows:[19]

·         T1 has been subclassified into T1a (≤2 cm in size) and T1b (>2–3 cm in size).

·         T2 has been subclassified into T2a (>3–5 cm in size) and T2b (>5–7 cm in size).

·         T2 (>7 cm in size) has been reclassified as T3.

·         Multiple tumor nodules in the same lobe have been reclassified from T4 to T3.

·         Multiple tumor nodules in the same lung but a different lobe have been reclassified from M1 to T4.

No changes have been made to the N (regional lymph nodes) classification. However, a new international lymph node map defining the anatomical boundaries for lymph node stations has been developed.
The M (distant metastasis) classifications have been redefined as follows:

·         M1 has been subdivided into M1a and M1b.

·         Malignant pleural and pericardial effusions have been reclassified from T4 to M1a.

·         Separate tumor nodules in the contralateral lung are considered M1a.

·         M1b designates distant metastasis.

Table 1. Stage Grouping Comparisons: Sixth Edition Versus Seventh Edition Descriptors, T and M Categories, and Stage Groupingsa,b
Sixth Edition T/M Descriptor (cm)	Seventh Edition T/M	N0	N1	N2	N3
T = primary tumor; N0 = no regional lymph node metastasis; N1 = metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension; N2 = metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s); N3 = metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s); M = distant metastasis.
aCells in bold indicate a change from the sixth edition for a particular TNM category.
T1 (≤2)	T1a	IA	IIA	IIIA	IIIB
T1 (>2–3)	T1b	IA	IIA	IIIA	IIIB
T2 (≤5)	T2a	IB	IIA	IIIA	IIIB
T2 (>5–7)	T2b	IIA	IIB	IIIA	IIIB
T2 (>7)	T3	IIB	IIIA	IIIA	IIIB
T3 invasion	T3	IIB	IIIA	IIIA	IIIB
T4 (same lobe nodules)	T3	IIB	IIIA	IIIA	IIIB
T4 (extension)	T4	IIIA	IIIA	IIIB	IIIB
M1 (ipsilateral lung)	T4	IIIA	IIIA	IIIB	IIIB
T4 (pleural effusion)	M1a	IV	IV	IV	IV
M1 (contralateral lung)	M1a	IV	IV	IV	IV
M1 (distant)	M1b	IV	IV	IV	IV