Small-cell lung cancer (SCLC) occurs almost exclusively in smokers and appears to be most common in heavy smokers. Historically, SCLC has been rare in never smokers. However, certain inherited mutations may increase the likelihood of developing SCLC.

It is very important to note that having inherited a genetic mutation does not mean a person will develop SCLC.

Although there are several different kinds of lung cancer, around 95% of lung cancers are either SCLCs or non-small cell lung cancers (NSCLCs).

What distinguishes SCLC from NSCLC is its rapid growth and the early development of widespread metastases. Although SCLC is initially very responsive to chemotherapy and radiation, the majority of patients will relapse within a few months to 1 year from initial therapy.

This article will look at whether SCLC is hereditary and whether a person can undergo genetic testing. It will also discuss the causes of and risk factors for SCLC.

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SCLC occurs when certain cells in the lungs grow quickly and uncontrollably, forming a tumor.

Cancers begin to develop when genetic mutations affect the genes that control the growth and division of cells or repair DNA that is damaged.

The majority of lung cancer cases are due to genetic changes known as somatic mutations, which are not hereditary. A person acquires them during their lifetime.

The National Organization for Rare Disorders notes that the two main somatic mutations related to SCLC affect the genes TP53 and RB1.

The TP53 gene provides instructions for creating a protein called p53, and the RB1 gene provides instructions for making pRB. Both proteins are tumor suppressors, which means they regulate cell growth and division.

However, in 2021, a group of researchers published a scientific paper that looked at 87 people with SCLC.

After analyzing 607 genes from each individual, the researchers found genetic mutations that increased the likelihood of developing SCLC in 43.7% of the study participants. Around 10% of these are heritable genetic mutations.

The authors of the paper conclude that certain heritable genetic mutations could make some people more likely to develop SCLC.

It is of note that if a person inherits a genetic mutation, this can increase their risk of developing cancer. It does not mean, however, that they will definitely develop cancer.

In addition, the American Cancer Society states that, although genes can play a role in the development of lung cancer, few lung cancers occur due to inherited mutations alone.

Genetic testing is when healthcare professionals look for potential inherited genetic mutations that may increase a person’s risk of developing certain kinds of cancer.

For some cancer types, a healthcare professional can also suggest genetic testing as a part of the diagnostic and staging process. This can help determine a person’s outlook and whether particular treatment options might be helpful.

Currently, however, doctors do not use genetic testing to diagnose SCLC. The Memorial Sloan Kettering Cancer Center notes that healthcare professionals and researchers know less about the genetic mutations that can lead to SCLC than they do about other genetic changes.

Smoking is the primary cause of SCLC. Tobacco smoke contains cancer-causing chemicals, or carcinogens, which damage the DNA in cells.

According to a 2020 review, 85% of lung cancer cases are the result of smoking.

Other risk factors include exposure to:

  • secondhand tobacco smoke
  • asbestos
  • radon, which is a naturally occurring gas that results from the breakdown of uranium in the rocks and soil
  • various chemicals, including arsenic, cadmium, silica, and coal products, through inhalation
  • diesel exhaust
  • air pollution

There are several ways in which a person may be able to lower their risk of developing SCLC.

Smoking tobacco is such a common cause of SCLC that the most effective preventive strategy is to not begin smoking.

However, for those who do smoke, quitting can lower the likelihood of developing SCLC. If a person quits before cancer develops, the lung tissue can begin to gradually repair itself.

A 2018 study looked at a group of people who have smoked 21.3 packs of cigarettes per year on average. The researchers compared the lung cancer rates of those who currently smoke and those who had quit within the previous 5 years.

They found that the individuals in the latter group were 39.1% less likely to develop lung cancer.

Other ways of lowering the risk of SCLC include reducing exposure to secondhand smoke, asbestos, and radon. However, this may sometimes be outside of a person’s control.

At the moment, doctors do not use genetic testing to diagnose SCLC.

Instead, a person should contact a healthcare professional if they experience any of the following symptoms:

If a healthcare professional suspects the cause of the above symptoms is SCLC, they may perform the following diagnostic tests:

  • laboratory tests of blood, urine, or samples of bodily tissue
  • chest X-rays or CT scans to look for lung tumors
  • a biopsy, in which doctors take some live cells from a person’s lungs to test them for cancerous growth

Cancer occurs due to genetic mutations that lead to an uncontrollable growth and division of cells.

A person can acquire these genetic mutations throughout their life. In some cases, certain hereditary genes can increase the risk of developing SCLC.

However, inherited genetic mutations are often not enough to cause cancer by themselves. Having inherited a genetic mutation does not mean a person will develop cancer. It means that it can increase the likelihood of that happening.

Smoking is the primary cause of SCLC. To help lower the risk of developing this type of cancer, a person should avoid smoking.