Small cell lung cancer (SCLC) is an aggressive type of lung cancer in which cells in the lungs multiply in an uncontrolled way. These cells then form a tumor. The cancer can spread to other areas of the body.

SCLC accounts for about 15% of lung cancers. A doctor can measure how far SCLC has spread by performing tests, such as PET scans, to identify the current stage of the disease.

In this article, we provide some information about the growth rate of SCLC, including its doubling time. We also look at treatment options for this type of cancer and the outlook for people living with it.

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SCLC grows and spreads much faster than other types of lung cancer, such as non-small cell lung cancer (NSCLC).

The American Cancer Society states that in 2 out of every 3 people with SCLC, the cancer will already have spread beyond their lungs when they receive a diagnosis.

The American Lung Association advises that people with an increased risk of lung cancer, such as those with a history of smoking, should undergo annual screening. The organization states that this screening could save lives.

Learn about the different stages of lung cancer here.

Research has shown that SCLC has a doubling time in the range of 25–217 days.

The National Cancer Institute (NCI) defines the doubling time as “the amount of time it takes for one cell to divide or for a group of cells, such as a tumor, to double in size.”

To calculate doubling time, doctors must first take two measurements of a cancerous nodule or tumor, estimating its diameter and volume. There must be a reasonable time interval between these measurements. They can then use an equation to determine the cancer’s doubling size.

A lower doubling time signifies a faster growing cancer. SCLC tends to have a low doubling time, reflecting its rapid growth.

Other ways to measure growth

Another important measure of cancer growth rate is the mitotic rate or mitotic count. The NCI describes this as the number of cells that are dividing within a given quantity of cancer tissue.

One study states that the mitotic rate for SCLC is 80 mitoses for every 2 square millimeters (mm2) of cancer tissue. This means that for every 2 mm2 of cancer tissue, each of 80 cancer cells has divided into two new cells. As the authors of this study note, this is a high mitotic rate.

See FAQs about how fast lung cancers can spread here.

In SCLC, some of the smaller cells in a person’s lungs grow in abnormal and uncontrolled ways. This growth may lead to the development of tumors, which are large lumps of tissue.

As with all cancers, SCLCs grow when the cancer cells keep on dividing. As well as growing larger in a person’s lungs, SCLC may also spread into other parts of the body. When a cancer spreads from its initial location to other body parts, this is known as metastasis.

As the NCI explains, SCLC can metastasize in several ways. For example, it can spread from the lungs into nearby organs simply by traveling into the tissue of those organs. SCLC cells can also spread around the body by traveling in the blood or via a person’s lymphatic system.

A 2020 review lists the following as common places to which SCLCs can metastasize:

Understanding the risk factors for SCLC may help some people prevent the condition or minimize its growth.

About 85% of all lung cancers have links to tobacco smoking, and the association between tobacco smoking and lung cancer is stronger in cases of SCLC than in most types of NSCLC. Therefore, remaining or becoming a nonsmoker can reduce a person’s risk of developing SCLC.

SCLC may also occur after exposure to secondhand smoke, radon, and asbestos. An individual can try to reduce their exposure to such substances to help prevent SCLC.

However, it is important to remember that SCLC is not always preventable.

Learn about five ways to lower the risk of lung cancer here.

The NCI states that most cases of SCLC are not curable. However, it may sometimes be possible to slow the growth of SCLC.

The most reliable method is to undergo some kind of cancer therapy, which could involve a combination of:

  • Chemotherapy: This is often the primary form of treatment for SCLC. Doctors may combine it with other treatments.
  • Radiation therapy: High energy rays can kill cancer in its early stages. Doctors often use this treatment alongside chemotherapy. In some cases, they may use it on the brain to stop the spread of the cancer there.
  • Immunotherapy: This treatment can boost a person’s immune system. Doctors may also create artificial versions of parts of the immune system that can destroy the SCLC cells.
  • Surgery: Doctors will rarely recommend surgery for those with SCLC because of how fast this cancer can spread.

The outlook for people with SCLC is generally less positive than it is for those with other types of lung cancer. The reason for this is that when the majority of people with SCLC begin to show symptoms of the disease, the cancer will already have metastasized.

Although chemotherapy may extend survival slightly, most people with SCLC die within 2 years of receiving a diagnosis. Therefore, a person with late stage SCLC may wish to weigh up the benefits of a potentially aggressive treatment against their quality of life.

It is important to remember that these figures are estimates that are based on the results of previous studies or treatments. A person can talk with a healthcare professional about how their condition is likely to affect them.

Learn more about the outlook for people with SCLC here.

Small cell lung cancer grows faster than other types of lung cancer, such as NSCLC. Most people receive a diagnosis of SCLC after it has already spread. However, a person can slow the spread of SCLC by undergoing treatments, such as chemotherapy or radiation therapy.

People at higher risk of getting SCLC, such as those with a history of smoking, should talk with their doctor to organize regular screenings for the condition. Early detection and treatment can significantly improve the outlook for people with this type of cancer.