Small-cell lung cancer is an invasive cancer that usually affects long-term smokers. It has two stages: limited and extensive. Each stage has a different outlook.

Small-cell lung cancer (SCLC) is a rare, aggressive lung cancer that accounts for 10–15% of all lung cancers in the United States. It usually affects people with a long history of smoking, but anyone can develop it.

Once someone receives a diagnosis of SCLC, doctors will try to see whether and where the cancer has spread. This is called staging. Doctors use the cancer stage to describe how much cancer is in a person’s body and to decide how best to treat it.

SCLC has two stages: limited stage and extensive stage. Doctors may use physical exams, imaging tests, biopsies, and other tests to determine the stage of cancer.

In limited stage SCLC, the cancer is on only one side of the chest and is usually in only one lung. It may also have reached the lymph nodes on that side.

Limited stage SCLC is usually contained enough to be treated with a single radiation field. Only 1 in 3 people with SCLC receive a diagnosis when their cancer is in the limited stage. In this stage, treatment may involve a combination of surgery, radiation, and chemotherapy.

Doctors diagnose SCLC in the extensive stage in 2 out of 3 people who have this type of cancer. At this stage, the cancer has spread:

  • throughout one lung
  • into the other lung
  • to lymph nodes on the other side of the chest
  • to other parts of the body

The cancer may also be considered extensive stage SCLC if it has spread to the fluid surrounding the lungs.

The goal of treatment for extensive stage SCLC is not to cure the cancer but to shrink it and help you live longer. Treatment at this stage of SCLC may include chemotherapy and, possibly, immunotherapy as first-line treatments.

The American Cancer Society uses a more formal staging system to describe lung cancer progression. It’s known as the TNM staging system and involves the following three factors:

  • Tumor (T): What are the size and extent of the main tumor? Has it grown into other areas?
  • Nodes (N): Has the tumor grown into nearby lymph nodes?
  • Metastasis (M): How far has the cancer spread to other organs, such as the adrenal glands, brain, liver, bones, or other lung?

Numbers or letters will appear with the T, N, and M to give more detail about each factor. In the TNM system, the earliest stage is stage 0 and the most advanced is stage 4.

This staging system is used for both non-small cell lung cancer and SCLC, but it’s considered less important for SCLC. The specifics of this system can be complex, so be sure to ask your doctor for a full explanation.

The outlook for someone with SCLC depends on the stage of the cancer, the person’s overall health, and the cancer’s overall response to treatment. In general, the outlook for people with limited stage SCLC is better than for those with extensive stage SCLC.

The SEER database tracks 5-year relative survival rates for various cancers. This system categorizes cancers into three groups:

  • Localized: The cancer has not spread outside the lung. This would relate to limited stage SCLC.
  • Regional: The cancer has spread beyond the lung to nearby lymph nodes or organs. This would relate to extensive stage SCLC.
  • Distant: The cancer has spread to other areas, such as the liver, bones, brain, or other lung. This would relate to a more advanced phase of extensive stage SCLC.

Here are the 5-year relative survival rates for SCLC based on SEER stage:

SEER stage5-year relative survival rate
localized (limited stage SCLC)30%
regional (extensive stage SCLC)18%
distant (advanced extensive stage SCLC)3%
all stages combined7%

However, these numbers don’t take everything into account.

People who receive an SCLC diagnosis now may have a better outcome, as treatments have improved over time. Your overall health and your specific cancer will also factor into your outlook.

SCLC is an aggressive form of lung cancer that mainly affects people with a long history of smoking. It has two stages: limited stage SCLC and extensive stage SCLC.

More people receive a diagnosis at the extensive stage since this type of lung cancer often does not have early symptoms.

People who receive a diagnosis of limited stage SCLC usually have a more favorable outlook than those who receive a diagnosis of extensive stage SCLC. However, every person’s response to treatment is different, and treatment options continue to improve over time.