Small-cell carcinoma

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at June 23, 2016
StartDiseasesSmall-cell carcinoma

Small-cell carcinoma, also known as small cell carcinomasmall-cell lung carcinoma (SCLC) and oat cell lung cancer due to the visual appearance of the cells under a microscope, is a highly malignant and rapidly spreading (metastatic) cancer that most commonly develops in the lungs. It often spreads through the bloodstream and lymphatic system to the rest of the body.


Definition & Facts

SCLC is characterized as the abnormal growth of smaller than normal cells which combine to form a tumor. SCLC first attacks the connective tissue around the lungs called the submucosa and peribronchovascular interstitium. These important layers protect the lungs and are aggressively overtaken by SCLC.

The American Cancer Society estimates that approximately 225,000 Americans will be diagnosed with lung cancer this year, and about 15 percent of these cases will be diagnosed as small-cell carcinoma. Of those who develop SCLC, 70 percent are diagnosed after it has spread to other organs or glands. Unfortunately, at that point, long-term survival rates diminish dramatically. SCLC has a low survival rate as compared to other types of cancers. However, it is also highly preventable as the primary cause is smoking, a preventable behavior.

Symptoms & Complaints

The symptoms of SCLC are similar to most other types of lung cancer and not altogether different from many diseases. Symptoms include shortness of breath, weight loss due to decreased appetite, physical weakness, chest pain, and cough with or without phlegm or blood present.

Because many of these symptoms mirror those of less serious conditions, the majority of patients do not seek medical care until the cancer has spread. By then, a patient’s complaints may grow to include abdominal pain or back pain, headache, achy bones, speech difficulties, and seizures.


Although some cases are linked to radon exposure or asbestos exposure, small-cell carcinoma is caused almost exclusively by smoking tobacco products or by breathing secondhand smoke. People who smoke should pay close attention to any early warning signs which point to lung trouble since this population is most susceptible to the disease.

When carcinogens (cancer-causing chemicals) from tobacco products are inhaled into the lungs, researchers believe that they mutate the genes in lung cells that prevent tumor growth. The abnormally small cancer cells invade the connective tissues, increase in number, and take advantage of the numerous blood vessels and lymphatic vessels which are present in the lungs. From here SCLC often metastasize to the liver, adrenal glands, lymph nodes, cervix, prostate, gastrointestinal tract, bladder, bones, and/or brain.

Diagnosis & Tests

Most cases of lung cancer are discovered when the lungs stop functioning properly as indicated by many of the symptoms listed above. The path to official diagnosis, however, has many steps. First, doctors will perform minimally-invasive tests such as examination of expelled mucus and blood tests for the presence of disease markers. They may also administer lung function tests.

Because most small-cell carcinoma patients don’t see a doctor until their cancer has spread, patients who complain of pain or discomfort in other areas of the body may undergo additional tests such as bone scans and ultrasounds to determine whether tumors are present anywhere in the body. Imaging tests such as X-rays, magnetic resonance imaging (MRI), computed tomography (CT), or positron emission tomography (PET) scans may also be used to detect the growth of any tumors.

In all cases, doctors must accurately identify where the cancer started as this will determine how to proceed in treating the patient. If any of these tests reveal abnormalities, a biopsy – removal of tissue from the lungs – will be performed so that doctors can study the cells under a microscope. This is the only definitive way to diagnose SCLC.

Treatment & Therapy

There are two primary stages of small cell carcinoma each of which call for a different course of treatment. Limited Stage (LS) SCLC is characterized by the presence of cancer cells just in the thorax, or chest cavity, and lymph nodes. Extensive Stage (ES) SCLC is diagnosed when cancer cells are discovered outside that area. LS-SCLC is treated with a combination of chemotherapy drugs and radiation therapy both of which have been shown to yield positive effects.

It is also standard practice to treat ES-SCLC patients with chemotherapy and radiation. In these late-stage cases, though, the radiation therapy is primarily used to relieve unpleasant symptoms such as bone pain or liver pain and to prevent the disease from spreading to the brain.

Regardless of which stage a patient is in, most respond very well to these treatments. However, the response does not last for long and eventually the cancer returns. Median survival rates for those with Limited Stage SCLC are between 14 and 20 months. For patients with Extended Stage SCLC, the range is eight to 13 months. 

Prevention & Prophylaxis

Because virtually all small cell carcinoma patients are smokers, the most effective way to prevent the development of this disease is to never smoke tobacco products. Those who do smoke should make every effort to quit. Individuals who don’t smoke can reduce their risk by avoiding secondhand smoke whenever possible.

It is beneficial for a patient to quit smoking even after he or she has been diagnosed with cancer. Individuals have been shown to respond more favorably to cancer treatment, feel better throughout the course, and face a reduced risk of developing other types of lung cancer after their initial diagnosis. Finally, testing one’s home for radon or asbestos is another preventative step which can be taken to reduce the risk of developing SCLC.