Oat cell lung cancer is the most common type of small cell lung cancer. Oat cell lung cancer is less common than large cell lung cancer, accounting for only 13 to 15 percent of all lung cancers, according to the Merck Manual. Oat cell is, however, more aggressive than large cell lung cancer. Nearly all cases of oat cell cancer are related to smoking. Because oat cell lung cancer grows so aggressively, the patient may already be in the last stages of the disease by the time of diagnosis.
Definition and Prognosis
Oat cell lung cancer is divided into two stages: limited, the early stage, and extensive, the late stage. Limited oat cell cancers are still contained within the chest and can be treated with radiation, Medline Plus reports. Extensive oat cell cancer has already spread beyond the lungs, and may be treated with chemotherapy and radiation. Treatment controls symptoms but does not cure the disease.
By the time most oat cell lung cancers are discovered, they're already extensive. Prognosis for survival is poor, with only 6 percent of patient surviving as long as 5 years. Without treatment, survival is 2 to 4 months. With treatment, patients with extensive last stage oat cell cancer live 6 to 12 months.
Respiratory and Chest Symptoms
Respiratory problems are common in last stage oat cell lung cancer because the tumors block the airways and decrease oxygen flow to the lungs. In advanced disease, supplemental oxygen is required due to collapsed lung areas, fluid accumulation in the lungs and narrowed airways from tumor compression. People in late stage oat cell cancer are often very short of breath. Persistent cough that produces blood tinged sputum is common. Pneumonia commonly develops as bacteria are trapped in the collapsed or damaged lungs.
As tumors advance in late stage oat cell cancer, pain in the chest may be caused by fluid accumulation or by the tumors growing into the chest wall. If the tumors grow into nerves in the center of the chest, hoarseness occurs.
Metastasis
Last stage extensive oat cell tumors almost always have spread to other areas of the body at the time of diagnosis. Metastasis to the bones, liver, kidney and brain are common in oat cell cancer. Symptoms depend on the area of metastasis. If the cancer spreads to the brain, memory loss, seizures and constant headache may develop, while bone metastasis may cause unremitting bone pain. If the cancer grows into the neck and esophagus, it becomes difficult to swallow, and the neck may swell.
If oat cell cancer invades the superior vena cava, a large blood vessel, pain and swelling of the face, chest wall and neck may occur, along with dizziness and vision problems. Invasion of tumors into the heart can lead to heart blockage or fluid accumulation around the heart, making it difficult for the heart to pump effectively.
