Small Cell Lung Cancer

January 24, 2025

This page was reviewed under our medical and editorial policy by Jyoti Malhotra, M.D., M.P.H., associate professor, Department of Medical Oncology & Therapeutics Research, City of Hope^® Orange County Lennar Foundation Cancer Center; and Jae Y. Kim, M.D., associate professor, Division of Thoracic Surgery, Department of Surgery, City of Hope Cancer Center Duarte

Small cell lung cancer (SCLC) is less common than non-small cell lung cancer (NSCLC). Each year in the United States, about 226,650 people are newly diagnosed with lung cancer, of which 10% to 15% are small cell lung cancers, according to the American Cancer Society.

This guide to small cell lung cancer is designed to help patients and their families learn more.

What Is Small Cell Lung Cancer?

Small cell lung cancer begins within the tissue of the lungs, vital organs responsible for breathing. This type of lung cancer is known to be fast-growing, and it may spread into other areas of the body before it is diagnosed.

Cancer may start anywhere in the lung. Each of the two lungs is divided into lobes, or sections. The right lung is larger, with three lobes, while the left lung has two lobes. The lungs help bring oxygen into the body and remove carbon dioxide. This is assisted by small airway tubes (bronchioles) and air sacs (alveoli) that fill the inside of the lungs.

Types of Small Cell Lung Cancer

There are two main subtypes of small cell lung cancer, along with some rare subtypes. Although each subtype begins in the lungs, they have slightly different characteristics.

Small Cell Carcinoma (Oat Cell Cancer)

This is the most common type of SCLC. It is typically fast-growing, and it may spread to other areas of the body quickly. It is referred to as oat cell cancer because the cancer cells are small and oval-shaped, like oats.

Small cell carcinoma most often begins in the lungs, but it may also originate in other areas of the body.

Combined Small Cell Carcinoma

This subtype is much more rare. Combined small cell carcinoma tumors contain a mix of both small cell and non-small cell cancer types, including adenocarcinoma and squamous cell.

What Causes Small Cell Lung Cancer?

Several risk factors are linked to small cell lung cancer, and the most important is smoking. Patients who currently or previously smoked cigarettes or tobacco products have an increased risk for developing the disease during their lifetime.

Other risk factors linked to small cell lung cancer include:

• Long-term exposure to secondhand tobacco smoke
• Previous radiation treatment, such as radiation therapy
• Imaging tests such as computed tomography (CT) scans
• Long-term exposure to certain workplace chemicals, including asbestos, tar, soot, nickel and beryllium
• Radon exposure in the workplace or home
• HIV (human immunodeficiency virus) infection
• Long-term exposure to air pollution
• Being a smoker who takes beta carotene supplements

The risk of developing lung cancer also increases with age.

Is Small Cell Lung Cancer Hereditary?

While smoking is the strongest risk factor for small cell lung cancer, research shows that some inherited genetic mutations may increase a person’s risk.

The gene mutations that may be linked to SCLC include:

• BRCA1
• BRCA2
• RAD51D

Cancers linked to genetic mutations may have improved outcomes and are thought to be more responsive to personalized treatments that target the specific mutations.

Symptoms

Symptoms may appear quickly after SCLC has developed. These are some of the most common symptoms of SCLC, but not all patients will experience all symptoms:

• Cough or wheezing, which may produce blood
• Breathing difficulty
• Fatigue
• Unexplained weight loss
• Difficulty swallowing
• Hoarseness
• Swelling around the neck or face

It is important to keep in mind that these symptoms may also be caused by health conditions other than lung cancer. Patients should always speak with their doctor if they notice any unexpected changes.

Lung nodules, which are small, abnormal areas on the lungs found on imaging tests, may also be a sign of SCLC. However, they may also be caused by other health conditions, such as scarring or infection.

Diagnosis

If a doctor suspects small cell lung cancer may be present, they’ll use a range of different diagnostic tests to learn more. These may include the following.

Physical exam: This is a thorough review of a patient’s medical history and a physical examination to look for any signs of SCLC.

Urine and blood tests: These tests are used both for diagnosis and to help monitor ongoing treatment.

Chest X-ray: Using X-rays and radiation, this imaging allows doctors to take internal pictures of the lungs and chest.

Imaging tests: Other imaging tests may also be used for both diagnosis and checking to see if the cancer has spread. These include CT scans, magnetic resonance imaging (MRI), bone scan and positron emission tomography (PET) scans.

Lung biopsy: During a biopsy, doctors remove a tissue sample from the lungs. It is examined under a microscope to look for cancer cells.

Thoracoscopy: This surgical procedure allows doctors to look inside the lungs for signs of cancer. An incision is made in the chest and a thoracoscope (a long, thin instrument with a light) is inserted into the body. It may also be used to take a tissue sample.

Bronchoscopy: A thin, flexible tube is inserted via the nose or mouth. With a camera on the end, it allows doctors to look for evidence of cancer. It may also be used to take a tissue sample for a biopsy.

Mediastinoscopy: Using a mediastinoscope (a long, thin instrument) inserted surgically into the chest, doctors are able to examine the lymph nodes, lungs and nearby tissue to look for signs of cancer.

Stages of SCLC

Each cancer is assigned a stage, which measures the size of the cancer as well as whether and where it has spread. Knowing the SCLC’s stage is important for determining treatment plans for each patient.

The stages of small cell lung cancer are limited-stage and extensive-stage.

Limited-stage small cell lung cancer: The cancer is contained within the lungs. Or, it may have spread into nearby areas, including the lymph nodes near the collarbone or the space between the lungs.

Extensive-stage small cell lung cancer: The cancer has grown past the lungs and nearby areas, moving into distant areas of the body.

Small Cell Lung Cancer Treatment

Several treatment options are available for small cell lung cancer. Each patient receives a personalized treatment plan, depending on the cancer type, stage, his or her overall health and personal preferences.

Small cell lung cancer treatments may include the following.

Chemotherapy for lung cancer: This treatment uses medication to destroy cancer cells. It is given in cycles and is taken either orally or intravenously.

Radiation therapy for lung cancer: High-energy X-rays or other kinds of radiation are targeted toward the tumor to destroy cancer cells. Radiation therapy may be used as a treatment, but it also may provide relief from side effects, which is known as palliative radiation therapy.

Surgery: Although not commonly used for small cell lung cancer, surgery may be used if the cancer is detected at an early stage. If surgery is used, it is often combined with either chemotherapy or radiation therapy.

Immunotherapy for lung cancer: This treatment uses medication to boost the patient’s immune system, helping it identify and destroy lung cancer cells.

Laser therapy: A precise and powerful laser is directed toward the tumor to destroy cancer cells. This is very rarely used for SCLC.

Additional treatments may be options for some patients, including clinical trials. These allow patients to participate in scientific research while also receiving the highest standard of care.

Who Treats SCLC?

After receiving a small cell cancer diagnosis, members of the patient’s care team will work together to identify the most targeted SCLC treatment options. The small cell lung cancer care team may include these experts the following specialists.

• Medical oncologists: Doctors who work with SCLC patients to pinpoint the most effective, least invasive treatments for their specific cancer subtype and stage
• Thoracic surgeons: Specialists who operate on diseases of the lungs and chest cavity
• Pulmonologists: Experts in diagnosing and treating conditions affecting the lungs Radiation oncologists: Specialists who may create a radiation therapy plan to help treat the patient’s small cell lung cancer

What Is the Survival Rate of Small Cell Lung Cancer?

The small cell lung cancer survival rate varies based on a number of factors. These include the subtype and stage of cancer; the patient’s age and overall health; how they respond to treatment; and whether certain mutations are detected in the cancer cells.

Scientists often use the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program Database to measure the five-year relative survival rate for small cell lung cancer. These numbers reflect the percentage of people with this cancer type who survived for five years or longer after diagnosis, compared to those who don’t have SCLC.

Between 2012 and 2018, the five-year relative survival rate for all SCLC was 7%, according to the American Cancer Society analysis. By stage, it was as follows.

• Localized: 30%.
• Regional: 18%.
• Distant: 3%.

Patients should always speak with their small cell lung cancer care teams to receive a prognosis tailored to their cancer subtype, stage and other factors.

Small Cell Lung Cancer Versus Non-Small Cell

Both small cell and non-small cell cancers begin in the lungs, but there are key differences between the two diseases.

Small cell lung cancer accounts for 10% to 15% of all lung cancer cases, making it less common than non-small cell lung cancer.

SCLC is more aggressive and grows faster than NSCLC.

Surgery is rare for SCLC, with chemotherapy, radiation therapy and/or immunotherapy being the most common treatment options. With NSCLC, surgery is common.

The average five-year relative survival rate for all stages combined of SCLC (7%) is lower than that for NSCLC (28%).