Small Cell Lung Cancer (SCLC)

What makes small cell lung cancer different

Lung cancers are divided into two main types: non-small cell lung cancer (about 85 percent) and small cell lung cancer. SCLC cells are small under the microscope and have neuroendocrine features, meaning they can make hormones. SCLC:

• grows and spreads quickly
• usually starts in the central airways
• often spreads to lymph nodes, brain, liver, bones and adrenal glands early
• is initially very sensitive to chemotherapy and radiation
• is almost always linked to smoking

Symptoms

Chest symptoms

• A cough that does not go away or changes
• Coughing up blood (hemoptysis)
• Shortness of breath and wheezing
• Chest pain
• Hoarseness
• Repeated chest infections

General symptoms

• Weight loss and loss of appetite
• Tiredness

Symptoms from spread

• Headaches, seizures or confusion (brain)
• Bone pain (bones)
• Belly pain or jaundice (liver)
• Swelling of the face and arms (superior vena cava syndrome)

Paraneoplastic syndromes

SCLC can produce hormones or trigger immune reactions that affect other parts of the body:

• SIADH: excess antidiuretic hormone causing low sodium (hyponatremia), with confusion, nausea and seizures
• Cushing's syndrome from ACTH production
• Lambert-Eaton syndrome: muscle weakness, especially in the hips and thighs
• Cerebellar degeneration and other neurological syndromes

Causes and risk factors

• Smoking: the main cause. Risk rises with the number of years and cigarettes smoked.
• Secondhand smoke
• Radon gas exposure at home
• Workplace exposures: asbestos, diesel exhaust, some chemicals
• Air pollution

SCLC in people who have never smoked is rare. See lung cancer in nonsmokers.

Diagnosis

• Chest X-ray and CT scan
• Biopsy: usually by bronchoscopy, endobronchial ultrasound (EBUS) or needle biopsy, to confirm SCLC
• Staging tests: PET-CT and brain MRI
• Blood tests, including sodium and liver tests

Stages

Doctors also use the TNM system to plan treatment.

Treatment

Limited stage

• Chemotherapy (usually cisplatin or carboplatin with etoposide) plus radiation therapy to the chest, given at the same time
• Immunotherapy with durvalumab after chemoradiation for eligible people, which improves survival
• Surgery for the rare very early tumors without lymph node spread, followed by chemotherapy
• Brain protection: prophylactic cranial irradiation or regular brain MRI scans to detect spread early

Extensive stage

• Chemotherapy plus immunotherapy (atezolizumab or durvalumab), followed by maintenance immunotherapy
• Radiation to the chest or to sites of spread, such as the brain or bones, to control symptoms
• At relapse: further chemotherapy (such as topotecan or lurbinectedin) and newer immunotherapies such as tarlatamab
• Clinical trials

Supportive and palliative care

Early palliative care improves quality of life, managing breathlessness, pain, cough, fatigue and emotional needs alongside cancer treatment.

Outlook

SCLC usually responds well to initial treatment, but it often returns within months to a couple of years. Survival is better for limited-stage disease, and some people with limited-stage SCLC are cured. Extensive-stage SCLC is rarely curable, but newer immunotherapy combinations have increased the number of people living beyond 2 years. Stopping smoking improves treatment outcomes at any stage.

Prevention and early detection

• Do not smoke, and get help to quit (1-800-QUIT-NOW in the US).
• Test your home for radon.
• The US Preventive Services Task Force recommends yearly low-dose CT screening for adults aged 50 to 80 with a 20 pack-year smoking history who currently smoke or quit within the past 15 years. Screening is more effective at finding non-small cell lung cancer, but it can detect some SCLC.

Frequently asked questions

What is small cell lung cancer?

Small cell lung cancer is a fast-growing type of lung cancer, making up about 13 to 15 percent of cases. It is strongly linked to smoking, usually starts in the central airways and tends to spread early to other parts of the body, including the brain, liver and bones.

What are the symptoms of small cell lung cancer?

Common symptoms include a persistent or changing cough, shortness of breath, chest pain, coughing up blood, hoarseness, weight loss and tiredness. Some people have symptoms from spread, such as headaches or bone pain, or from hormones made by the cancer, such as confusion from low sodium.

What is the difference between limited and extensive stage?

Limited stage means the cancer is confined to one side of the chest and nearby lymph nodes and can be treated within one radiation field. Extensive stage means it has spread further, to the other lung, distant lymph nodes or other organs. About two thirds of people are diagnosed at the extensive stage.

What is the survival rate for small cell lung cancer?

Survival depends mainly on stage. Some people with limited-stage disease are cured with chemotherapy and radiation, while extensive-stage disease is usually not curable but can be controlled for a time. Newer immunotherapy combinations have improved long-term survival. Your cancer team can give the most relevant estimate.