Small-Cell Lung Cancer

What Is It?

Small-cell lung cancer has been called oat-cell cancer because the cells resemble oats when seen under a microscope. This cancer usually originates in the lung's large central airways (the bronchi), and it accounts for about 20 percent of all lung cancers. In some cases, small-cell tumors also will include cells that have non-small-cell features. This condition is called a mixed tumor.

All types of lung cancer are associated strongly with smoking. About 90 percent of people who get small-cell lung cancer are either current or past smokers.

Because this type of cancer starts in special hormone-producing cells in the lung, it can cause unique sodium and water problems. For example, the tumor cells may secrete adrenocorticotropic hormone, causing Cushing's disease. The tumors also may secrete antidiuretic hormone, leading to water retention and low sodium, which causes confusion. Small-cell cancer also can cause a specific type of weakness caused by antibodies produced as a result of the cancer. Small-cell lung cancer is among the fastest-growing cancers. In two-thirds of patients, the cancer already will have spread (metastasized) at the time of diagnosis. The cancer can spread easily because of the constant flow of fluids through the lungs. These fluids consist of blood and lymph (a protein-filled fluid from the lymphatic system). The fluids can carry cancer cells to lymph nodes, the heart, the other lung and to organs outside of the chest. Small-cell lung cancers spread more commonly to the brain, liver, adrenal glands and bone.

Symptoms

Although some cancers do not have any symptoms at first, others are diagnosed during an evaluation for any of the following:

• A persistent cough
• Coughing up of blood (hemoptysis)
• Shortness of breath or wheezing
• Unexplained weight loss or loss of appetite
• Fatigue
• Difficulty swallowing
• Pain in the chest, shoulder or arm
• Recurrent pneumonias in the same place
• Bone pain
• Hoarseness
• Headaches, confusion or seizures
• Swelling of the face, neck or upper extremities

Diagnosis

Lung cancer often is discovered first on a chest X-ray, on which it appears as a gray or whitish area. Other imaging studies, such as computed tomography (CT) or magnetic resonance imaging (MRI), are used to further determine the size, shape and location of the tumor as well as to locate areas where the tumor has spread. This helps to find the best place to obtain a sample of the tumor to diagnose small-cell versus other types of lung cancer such as squamous cell or adenocarcinoma of the lung. The type of cancer affects what treatment you should get.