Small Cell Lung Cancer Stages

After someone is diagnosed with small cell lung cancer (SCLC), doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes where the cancer is in the body. It helps determine how best to treat it. Doctors also use a cancer’s stage when talking about survival statistics.

How is the stage determined?

The stage of SCLC is based on the results of physical exams, biopsies, imaging tests, and any other tests that have been done (as described in Tests for Lung Cancer).

Limited versus extensive stage

For treatment purposes, most doctors use a 2-stage system that divides SCLC into limited stage and extensive stage. For limited-stage cancer, a person might benefit from more aggressive treatments such as chemotherapy combined with radiation therapy to try to cure the cancer. For extensive-stage disease, chemotherapy in combination with immunotherapy is likely to be a better option to control (not cure) the cancer.

Limited stage

This means that the cancer is only on one side of the chest and can be treated with a single radiation field. This generally includes cancers that are only in one lung, and that might also have reached the lymph nodes on the same side of the chest.

Cancer in lymph nodes above the collarbone (called supraclavicular nodes) might still be considered limited stage as long as they are on the same side of the chest as the cancer. Some doctors also include lymph nodes at the center of the chest (mediastinal lymph nodes) even when they are closer to the other side of the chest.

What is important is that the cancer is confined to an area that is small enough to be treated with radiation therapy in one treatment area. Only about 1 out of 3 people with SCLC have limited-stage cancer when it is first found.

Extensive stage

This describes cancers that have spread widely throughout the lung, to the other lung, or to other parts of the body (including the bone marrow). Many doctors consider SCLC that has spread to the fluid around the lung and/or heart to be extensive stage as well. About 2 out of 3 people with SCLC have extensive disease when their cancer is first found.

The TNM staging system

A more formal system to describe the growth and spread of lung cancer is the American Joint Committee on Cancer (AJCC) TNM staging system, which is based on 3 key pieces of information:

• The size and extent of the main tumor (T): How large is the tumor? Has it grown into nearby structures or organs?
• The spread to nearby (regional) lymph nodes (N): Has the cancer spread to nearby lymph nodes?
• The spread (metastasis) (M) to other organs of the body: Has the cancer spread to distant organs such as the brain, bones, adrenal glands, liver, or the other lung?

Numbers or letters appear after T, N, and M to provide more details about each of these factors. Higher numbers mean the cancer is more advanced. Once the T, N, and M categories have been determined, this information is combined in a process called stage grouping, to assign an overall stage. For more information, see Cancer Staging.

In the TNM system, the earliest stage is stage 0 (also called carcinoma in situ, or CIS). The other main stages range from I (1) through IV (4). Some of these stages are broken down further with letters or numbers. As a rule, the lower the stage number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. And within a stage, an earlier letter (or number) means a lower stage.

The same TNM staging system is used for both SCLC and non-small cell lung cancer (NSCLC), although it’s generally not as important for SCLC. For more detailed information about this system, see Non-Small Cell Lung Cancer Stages. Staging with the TNM system can be complex, so if your health care team is using it, ask them to explain it to you in a way you understand.