Lung Cancer Staging

By Rey Maquiling (RN pending – Dec 2011)

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Staging for lung cancer is particularly helpful because it determines the extent to which the cancer cells have spread or metastasized. It also helps oncologists in exploring the possible treatment option for individual patients. Depending on what treatment is indicated for the patient, staging ultimately helps in determining the prognosis of the disease.

Cancer staging varies for the two major categories of lung cancer: non-small cell lung carcinoma and small cell lung carcinoma. It is normally done prior to surgery and consists of a series of imaging tests and biopsies.

For both NSCLC and SCLC, there are two classifications of staging:

Clinical Stage – this is solely based on the results of biopsies, imaging tests and other pertinent laboratory findings.
Pathological Stage – normally found after surgery. It is the sum total of all results on the clinical stage plus the findings from the surgery.

Basic Staging for Non-Small Cell Lung Carcinoma

In a nutshell, the numbers 0 to 4 have a significant role in the staging of all cancers. As the number goes higher, it signifies that the spread of the cancer grows and may ultimately, affect other organs.

Stage 0

The cancer cells are localized and present only in a few layers of the cells. This means the tumor has not spread past the inner lines of the lungs. This is otherwise known as a carcinoma in situ.

Stage 1

The cancer cells are still localized but are affecting a good part of the lung. It has not spread to the lymph nodes yet. It is divided into two parts depending on the size on the tumor. When it is less than 3cm, it said to be in the Stage 1A.When it is more than 3cm, it said to belong to the Stage 1B.

Stage 2

This stage signifies that the cancer cells has spread to nearby lymph nodes or may have a prominent size and has affected certain areas of the main bronchus or has invaded the lung lining.  It is divided into two stages: Stage 2A (the size is 3cm or less) and Stage 2B (the size is more than 3cm).

Stage 3

This stage means the malignant cancer cells have spread to nearby tissues other than lungs.  The cancer is confined to the chest area.  Stage 3A can be a significantly large tumor affecting nearby lymph nodes or a small tumor that have spread to lymph nodes further away from its location.  Stage 3B can be any size of the tumor invading distant lymph nodes, a tumor invading other tissues and structures in the chest like the heart or esophagus or a tumor coupled with a malignant pleural effusion.

Stage 4

This stage in lung cancer has spread into other parts of the body other than the chest.

TNM Staging

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The TNM staging is another way of staging lung cancers or other cancers which as been developed and revised recently by the American Joint Committee on Cancer and the Union Internationale Contre le Cancer. TNM is an acronym that stands for tumor size, node involvement and metastasis. It is utilized both for SCLC and NSCLC cases but more often in the latter.

Tumor Size is described as follows:

TX: The tumor is only found in cytological studies of the sputum yet cannot be assessed or found through imaging tests.
T0: No tumor or evidence of a tumor is found.
Tis: Only the upper layers of the cells are affected by the tumor. This is also known as carcinoma in situ.
T1: The tumor is 3cm or less when measured across. It is surrounded by the lung or its pleura yet does not affect the main bronchus.
T2: Tumor is more than 3cm and is affecting one of the main bronchus – 2cm or more from the carina. It can also be a tumor that has invaded the visceral pleura or causes an incomplete expansion of the lung or an obstruction infection of the lung but not the entire lung.
T3: This tumor has invaded the chest wall, pericardium, diaphragm and pleura. It can also involve the main stem bronchus less than 2cm from the carina, or a tumor that can cause a complete lung collapse or obstructive infection of the entire lung.
T4: This tumor has invaded the heart and its great vessels, trachea, esophagus, carina or vertebral body. It can also be separate tumor nodules affecting the same lobe of a lung or a tumor with and associated malignant pleural effusion.

Node involvement is defined as follows:

NX: The regional lymph nodes are difficult or are impossible to assess.
N0: The regional lymph nodes do not signify metastases.
N1: There is metastasis around the bronchi and/or involvement of hilar lymph nodes and nodes within the lungs.
N2: There is a same-side metastasis of mediastinal and/or subcarinal lymph nodes.
N3: The involvement reaches the other side of the affected lung.

Metastasis is defined as follows:

MX: Unable to see or assess metastasis.
M0: There is no distant metastasis.
M1: There is distant metastasis.

Below is the classification of the stages:

Stage 1A: T1, N0, M0
Stage 1B: T2, N0, M0
Stage 2A: N1, M0
Stage 2B: T2, N1, M0 or T3, N0, M0
Stage 3A: T1 to T2, N2, M0 or T3, N1 to N2, M0
Stage 3B: T (any), N3, M0 or T4, N (any), M0
Stage 4: T (any), N (any), M1

Staging for Small Cell Lung Carcinoma

The staging for SCLC is much simpler. It is only divided into two stages that differ in whether or not the cancer is localized, what lymph nodes are involved and what is the best treatment option.

Limited Stage – Cancer cell is only affecting one lung and in some cases, may involve the lymph nodes on the same side of the chest. Since it is usually confined to one area, it is small enough to be treated with radiation therapy.
Extensive Stage – The cancer has spread to the other lung including the lymph nodes on the opposite side of the chest and may even affect the fluid surrounding the lung and other distant organs.

For someone who may have just received the bad news of cancer, dealing with staging may be a difficult process.  However, in reality, it is a very important aspect in understanding the progression and best treatments for lung cancer.