CONTENT:

7.2 The TNM Lung Cancer Staging System
7.2.1 The Basics of the TNM Lung Cancer Staging System for NSCLC
7.2.2 The AJCC TNM Staging Classification (7^th Edition)

 

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7.2  The TNM Lung Cancer Staging System for NSCLC

 
The ‘TNM’ staging system describes:

T – the size and position of the tumor.

N – the presence of spread into the lymph nodes.

M – the presence of metastases or ‘secondary’ lung cancer.

Each category is qualified by a number.

A small localized lung cancer that has not spread will be a T1, N0, M0.

 

7.2.1 The Basics of the TNM Lung Cancer Staging System for NSCLC

 
Tumour (T)

The T stages for lung cancer are:-

 
T1a – the lung cancer is smaller than 2 cm and is localized to the lung.

T1b – the lung cancer is between 2 and 3 cm and is localized to the lung.

T2 – the lung cancer is between 3 and 7 cm or has grown into the main bronchus, more than 2 cm below the carina.

Or, the lung cancer has invaded the pleura.

Or, the lung cancer has obstructed the bronchus and is associated with lung collapse.

T2 lung cancers that are 5 cm or smaller are T2a;  those larger than 5 cm are T2b.

T3 – the lung cancer is larger than 7 cm or has grown into the chest wall, the diaphragm, the pleura, or the pericardium or is associated with lung collapse or there is more than one tumor nodule in the same lobe of the lung.

T4 – the lung cancer has invaded the mediastinum, the heart, a major blood vessel, the trachea, the carina, the spine, the esophagus, the laryngeal nerve, or there are tumour nodules in more than one lobe of the same lung.

 

 
 

Nodes (N)

The N stages for lung cancer are:-

 
N0 – there is no lung cancer in any lymph nodes.

N1 – there is lung cancer in the proximal lymph nodes.

N2 – there is lung cancer in mediastinal hilar lymph nodes, but on the same side as the affected lung or there is lung cancer in carinal lymph nodes.

N3 – there is metastatic lung cancer in lymph nodes on the opposite side of the chest, in cervical or apical lymph nodes.

Metastases (M)

The M stages for lung cancer are:-

 
M0 – the lung cancer has not spread to another part of the lung or any other part of the body.

M1a – lung cancer has spread to both lungs, or there is a malignant pleural or pericardial effusion.

M1b – there are lung cancer metastases to distant sites such as the liver or bones.

 

 
 

7.2.2 The AJCC TNM Lung Cancer Staging Classification (7^th Edition)

 
The main aim of a staging system is to define patient prognosis, but there are other uses.

There is a requirement for a common nomenclature (naming of terms for lung cancer)  for patient groups that may form a ‘directive’ or ‘algorithm’ (set of rules) for patient treatment.

The International Association for the Study of Lung Cancer ( IASLC)  Lung Cancer Retrospective Staging Project produced recommendations for the International Union Against Cancer (UICC) and for the American Joint Committee on Cancer (AJCC) that led to the production of the 7th edition of the TNM classification system for lung cancer.

The International Staging Committee of the IASLC launched a Prospective Lung Cancer Staging Project in May 2009. The IASLC project was designed to assess the validity of each component of T, N, and M and the other factors relevant to lung cancer staging and prognosis.

The development of the 2009 revised staging system for Non-Small Cell Lung Cancer (NSCLC) by the IASLC International Staging Committee involved a large amount of international collaborative work and data analysis. This revised staging system was developed with evidence-based data; that is why there are so many staging subgroups.

These staging subgroups were determined using ‘outcome measures’ of ‘overall survival‘ (OS).

 

 
 

Figure 7.7  Overall Survival (OS) According to Tumor Size (T).
(Modified from: Detterbeck et al, 2009).

 

 

Lung Cancer Staging: Past and Present

 
Over time, there are factors that change the approach to such ‘treatment groupings.’  For lung cancer, new treatment approaches are rapidly developing, and these may affect patient prognosis. There are also advances in imaging that may affect how a stage of cancer is given to a patient.

The implementation of lung cancer screening and tumor detection (e.g., by LDCT screening) can alter the range and types of lung tumor that are diagnosed.

The IASLC lung cancer staging system has been developed to meet the requirement for a common lung cancer staging nomenclature.

An important part of patient prognosis includes an emphasis on histopathologic lung tumor staging; clinical staging is more practical because it can guide treatment decisions from the start.

It must be remembered that the present cancer staging systems are anatomically based.

In the future, refinements or new staging systems may include biological behavior or gene profiling.

 

 
 

Figure 7.8   Overall Survival (OS) According to Lymph Node Involvement (N).
(Modified from: Detterbeck et al, 2009)

 

 

Biological behavior and Lung Cancer Staging

 
Clinical observations have indicated that there may be distinct types of biological behavior that affect lung cancer prognosis in patients.

There are four types of ‘biological behavior’ that requires further investigation to develop prognostic markers:

1. There are lung cancers that are characterized by a tendency to spread to regional lymph nodes.
2. There are lung tumors that are characterized primarily by direct local invasion.
3. There are lung tumors with a tendency to develop additional foci of cancer within the lung.
4. There are lung tumors with a tendency for systemic metastases.

 

Figure 7.9  Overall Survival (OS) According to the presence of Metastases (M)
(Modified from: Detterbeck et al, 2009)

 

 
The American Cancer Society (ACS) has produced a summary of the AJCC 7^th Edition Lung Cancer Staging: To view this summary click here.

Below is a summary of the staging categories:

T: Tumor

TX       The primary tumor cannot be assessed, or a tumor is proven by the presence of malignant cells in sputum or bronchial washings but is not visualized by imaging or bronchoscopy.

T0       No evidence of primary tumor

Tis      Carcinoma in situ

T1       Tumor < 3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).

T1a     Tumor < 2 cm in greatest dimension

T1b     Tumor > 2 cm but < 3 cm in greatest dimension

T2       Tumor > 3 cm but < 7 cm or tumor with any of the following features (T2 tumors with these features are classified T2a if < 5 cm):

• Involves main bronchus, > 2 cm distal to the carina.
• Invades visceral pleura.
• Associated with atelectasis or obstructive pneumonitis that extends to the hilar region but does not involve the entire lung.

T2a     Tumor > 3 cm but < 5 cm in greatest dimension

T2b     Tumor > 5 cm but < 7 cm in greatest dimension

T3       Tumor > 7 cm or one that directly invades any of the following:

• Chest wall (including superior sulcus tumors), diaphragm, phrenic nerve, mediastinal pleura, parietal pericardium.
• Tumor in the main bronchus < 2 cm distal to the carina but without involvement of the carina.
• Associated atelectasis or obstructive pneumonitis of the entire lung.
• Separate tumor nodule(s) in the same lobe.

T4       Tumor of any size that invades any of the following:

• Mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, carina.
• Separate tumor nodule(s) in a different ipsilateral lobe.

 

 
 

N: Nodes

NX      Regional lymph nodes cannot be assessed

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: Metastases

MX      Distant metastasis cannot be assessed

M0      No distant metastasis

M1      Distant metastasis

M1a    Separate tumor nodule(s) in a contralateral lobe
tumor with pleural nodules or malignant pleural/ pericardial effusion

M1b    Distant metastasis

 

Figure 7.10  Diagram of the Lymph Node Stations, 1 to 6.

 

 

Figure 7.11  Diagram of the Lymph Node Stations, 7 to 14.

 

 

 
 

References

American Joint Committee on Cancer (AJCC). (2009). Lung Cancer Staging. 7^th Edition. (Retrieved 26^th Feb 2015): http://cancerstaging.org/references-tools/quickreferences/documents/lungmedium.pdf

Detterbeck FC, Boffa DJ, Tanoue LT. (2009). The new lung cancer staging system. Chest 136(1), 260. (Retrieved 26^th Feb 2015): http://journal.publications.chestnet.org/article.aspx?articleid=1089923

More references for this section are on this page .

Patient Information

American Cancer Society (ACS) summary of the AJCC 7^th Edition Lung Cancer Staging: (Retrieved 26^th Feb 2015): http://cancerstaging.org/references-tools/quickreferences/documents/lungmedium.pdf

NCCN Cancer Staging Guide for Patients. (Retrieved 26^th Feb 2015): http://www.nccn.org/patients/resources/diagnosis/staging.aspx

More patient information for this section is on this page .

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