Small cell lung cancer is a fast-growing and fast-spreading form of lung cancer. There are two main types of small cell lung cancer: oat cell carcinoma and combined-small cell lung cancer.

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All forms of lung cancer fall under one of two subtypes: small cell lung cancer and non-small cell lung cancer (NSCLC). Small cell lung cancer includes around 15% of cases, while 85% of lung cancers classify as NSCLC.

Lung cancer, or bronchogenic carcinoma, is the second most common type of cancer in the United States and the leading cause of cancer death, accounting for a quarter of all cancer mortality. Approximately 225,000 people receive a diagnosis of the disease in the U.S. annually.

This article overviews small cell cancer and its symptoms, causes, diagnosis, and treatments. We also look at the general outlook, compare it with NSCLC, and answer some frequently asked questions.

Small cell lung cancer (SCLC) has a very high growth rate. It spreads rapidly from early on and often has a negative outlook.


There are two subtypes of SCLC: oat cell carcinoma and combined SCLC.

Combined SCLC is where SCLC develops alongside components of NSCLC, such as adenocarcinoma.


There are also two main stages of SCLC: limited stage and extensive stage.

In limited-stage SCLC, the disease is only present in one of the lungs and sometimes the lymph nodes in the chest on the same side.

The extensive stage refers to SCLC that spreads to:

  • the other lung
  • lymph nodes on the opposite side of the chest
  • other organs

In some cases, cancer that spreads to the fluid surrounding the lung classifies as the extensive stage.

The symptoms of SCLC vary depending on the location and stage. They tend to appear the same as NSCLC and can include the following:

  • coughing that worsens or does not go away
  • chest pain
  • shortness of breath
  • wheezing
  • coughing up blood
  • fatigue
  • unexplained weight loss

Due to the fast-growing and fast-spreading nature of SCLC, symptoms often begin 8–12 weeks before the presentation of the tumor.

Around two-thirds of SCLC diagnoses occur during the extensive stage when cancer has spread to other parts of the body. Because of this, people may experience different symptoms specific to the area that cancer affects.

There is a strong association between tobacco carcinogens and cancer, particularly with SCLC. Smoking tobacco accounts for around 85% of all lung cancer cases, and other risk factors include:

  • tobacco smoke
  • cigar smoke
  • secondhand smoke
  • radon exposure
  • asbestos exposure
  • inhaled chemicals
  • diesel exhaust fumes
  • air pollution
  • arsenic in drinking water
  • radiation therapy to the lungs
  • family history of lung cancer

The risk of developing lung cancer from cigarette smoke exposure can be greater or less, depending on the dose. The following factors define the dose:

  • type of cigarette
  • length of inhalation
  • filter presence

A diagnosis of SCLC involves reviewing a person’s symptoms and medical history. If these indicate the possibility of the disease, a doctor may suggest the following diagnostic tests:

The main treatment types for lung cancer are:

The most appropriate type of treatment depends on which stage the cancer is in. For SCLC in the limited stage, the goal is to try and treat the cancer, usually through radiation therapy and chemotherapy.

The goal of treatment in the advanced stage is primarily to manage symptoms rather than cure the disease. Other palliative care methods are also available.

If SCLC is in the limited stage and people have chemotherapy and radiation treatment, there is an 80% chance of surviving for the following 2 years. This decreases to a 15% survival rate after 5 years.

The outlook is usually negative for extensive SCLC. Around 70% of the time, the cancer has already spread throughout the body by the time of diagnosis. Even with chemotherapy, SCLC usually causes mortality within 24 months, with less than 2% of people surviving for 5 years after diagnosis.

NSCLC makes up 85% of lung cancer cases and includes various subtypes, the main ones being:

The main difference is that SCLC is more aggressive, while the likelihood of curing forms of NSCLC is higher.

Below are some frequently asked questions regarding SCLC and NSCLC.

What is the survival rate of SCLC without treatment?

The survival rate depends on the stage, but without treatment, the average survival rate is 2–4 months after diagnosis.

What are the complications of SCLC?

Most complications stem directly from SCLC or treatment side effects, but additional complications may include:

  • paraneoplastic syndromes, a group of rare conditions that cancer can lead to
  • symptoms of myasthenia gravis, a relatively rare neuromuscular disease
  • syndrome of inappropriate antidiuretic hormone secretion, where the body produces too much antidiuretic hormone, which affects kidney function

Small cell lung cancer is one of the two main classifications of lung cancer. The subtypes of this type of cancer are oat cell carcinoma and combined small cell lung cancer.

These types of cancers grow and spread rapidly, making them difficult to diagnose and treat during the early stages.

The main risk factor for small cell lung cancer is using tobacco. Other causes include environmental factors, such as exposure to pollutants.