Small Cell Lung Cancer

Small cell lung cancer (SCLC) is an aggressive disease characterized by rapid, uncontrolled growth of malignant cells in the lung that eventually form a tumor. Small cell lung carcinoma is considered to be a neuroendocrine carcinoma because the cancer cells have features of nerve and endocrine cells and can spread quickly to other areas of the body, such as the liver, adrenal glands, bone, and brain. Small cell lung cancer cells can act like tiny glands and can further cause a condition known as paraneoplastic disorder, in which the cancer cells secret chemical and hormones that cause a range of symptoms, such as abnormal blood mineral levels, high blood sugar, muscle weakness, or neurological symptoms. There are two types of small cell lung cancer: 1) oat cell small cell lung cancer, and 2) combined small cell lung carcinoma. Small cell carcinoma is categorized into two main stages: 1) limited-stage small cell carcinoma, which is possibly curable in 20-25% of individuals, and 2) extensive stage small cell carcinoma, which is difficult to treat. Limited-stage small cell lung cancer – In this stage, the cancer is in the lung and may spread to the area between the lungs or the lymph nodes above the collarbone. Extensive-stage small cell lung cancer – In this stage, the cancer has spread outside of the lung to the area between the lungs, the lymph nodes above the collarbone, or other places in the body.

There are several alternative names for small cell lung cancer, including combined small cell lung carcinoma, extensive-stage small cell carcinoma, limited-stage small cell carcinoma, oat cell carcinoma, and SCLC.

Smoking is the major cause of small cell lung cancer. The earlier an individual began smoking, the more often they smoke, and the more years they smoke all increase the risk of lung cancer. Additional risk factors for developing small cell lung cancer include exposure to secondhand smoke, exposure to workplace chemicals, such as asbestos, arsenic, chromium, beryllium, nickel, soot, or tar, exposure to radiation, exposure to air pollution, having a family history of lung cancer, being infected with the human immunodeficiency virus (HIV), taking beta carotene supplements, and aging.

While early small cell lung cancer rarely has symptoms, later symptoms may include loss of appetite, unexplained weight loss, fatigue, persistent or worsening coughing, wheezing, shortness of breath (dyspnea), hoarseness, chest discomfort or pain, pain in the shoulder or arm, difficulty swallowing (dysphagia), swelling of the face or neck veins, bone pain, swollen lymph nodes, headaches, confusion, or seizures, recurrent lung infections, such as bronchitis or pneumonia, jaundice (yellowing of skin and whites of eyes), numbness or tingling in hands, arms, feet, or legs, and coughing up blood (hemoptysis).

By the time small cell lung cancer is often discovered, it has usually already spread to other parts of the body; therefore, this cancer cannot be cured by surgery alone. For this reason, the main treatment for small cell lung cancer is a combination of surgery, chemotherapy, radiation therapy, immunotherapy, and supportive therapy. While, for most patients with small cell lung cancer, current treatments do not provide a cure, about 25% of patients with limited-stage small cell lung cancer can be cured with early treatment with chemotherapy and radiation therapy. Surgery – Surgery for limited-stage small cell lung cancer may be performed if the cancer is in only one lung and nearby lymph nodes. However, small cell lung cancer is most often found in both lungs; therefore, surgery alone is not frequently used. If surgery is performed, the surgeon will remove all visible cancer and the adjacent lymph nodes. Surgery may be used in combination with chemotherapy and/or radiation therapy. Chemotherapy – Chemotherapy uses drugs that kill cancer cells or stop them from forming and can be administered orally (pills), intravenously (systemic chemotherapy; IV), intrathecally (directly into the spinal fluid), or directly into an organ or cavity (regional chemotherapy) and includes the drug regimen, platinum-based chemotherapy (etoposide combined with cisplatin or carboplatin) or irinotecan, for small cell lung cancer. Chemotherapy may be used in combination with surgery and/or radiation therapy. Radiation therapy – Radiation therapy uses high-energy doses of radiation, protons, or other radiation to kill cancer cells. External radiation therapy directs the radiation at the cancer and may be used to treat small cell lung cancer or as a palliative therapy to help relieve pain or symptoms. Preventative radiation therapy may be administered to the brain (prophylactic cranial irradiation; PCI) for small cell lung cancer to reduce the risk of cancer metastasis (spread) to the brain. Radiation therapy may be used in combination with surgery and chemotherapy. Immunotherapy (Biological therapy) – Immunotherapy uses a patient’s immune system to attack cancer cells and includes immune checkpoint inhibitors for advanced small cell lung cancer such as CTLA-4 inhibitor therapy (ipilimumab) and PD-LI inhibitor therapy (pembrolizumab, nivolumab , atezolizumab, and durvalumab). Supportive therapy – Patients with small cell lung cancer may need assistance with breathing, which includes the use of bronchodilators and supplemental oxygen therapy.

There are several online, local, national, and international support groups for small cell lung cancer, including the following: American Lung Association - https://www.lung.org/lung-health-diseases/lung-disease-lookup/lung-cancer/patients/find-support/support-groups CancerCare - https://www.cancercare.org/diagnosis/lung_cancer Smart Patients - https://www.smartpatients.com/forums/lung-cancer

The outcomes (prognosis) for small cell lung cancer depend on the stage of the disease, how far the cancer has spread, and the patient’s overall health. Due to the rapid growth and spread (metastasis) of small cell lung cancer, the outcomes (prognosis) are poor, as the 5-year survival rate is only about 6%. However, the survival rate can be higher if small cell lung cancer is treated early. Small cell lung cancer frequently recurs after treatment.

Since small cell lung cancer frequently grows near the large blood vessels in the chest, such as the superior vena cava, these blood vessels can become blocked by a tumor, decreasing blood flow to the brain, one of which is called superior vena cava syndrome and is a medical emergency. Symptoms of superior vena cava syndrome include headache, bloated appearance of the head, red face, and bulging chest and neck veins.

If you experience any symptoms of small cell lung cancer, such as loss of appetite, unexplained weight loss, fatigue, persistent or worsening coughing, wheezing, shortness of breath (dyspnea), hoarseness, chest discomfort or pain, pain in the shoulder or arm, difficulty swallowing (dysphagia), or coughing up blood (hemoptysis), make an appointment with your doctor as soon as possible.

Since 90% of individuals with small cell lung cancer are either current or past smokers, quitting smoking and avoiding secondhand smoke is the most effective way to decrease the risk of developing the disease. Individuals aged 55-to-80 years with a long-term history or smoking, or those who currently smoke, should undergo screening for lung cancer. Early detection and treatment of small cell lung cancer can increase the possibility of a cure, as nearly 25% of patients with this cancer can be cured with chemotherapy and radiation therapy.