What Is Lung Cancer?
Lung cancer is a disease in which cells in the lungs begin to grow out of control and interfere with normal lung functions such as breathing. The vast majority of lung cancer cases fall into one of two categories: non–small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).
NSCLC. NSCLC is the most common type of lung cancer, making up nearly 80 percent of all cases. This type of lung cancer grows and spreads more slowly than the other major type and is therefore more treatable. NSCLC is divided into three subtypes: squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. The five-year survival rate for patients with NSCLC is less than 25 percent (Jemal A et al 2006).
SCLC. SCLC accounts for 20 percent of all lung cancer cases. Its small cells can rapidly reproduce to form large tumors that quickly spread to the lymph nodes and other parts of the body. This type of lung cancer is almost always caused by smoking or secondhand smoke. SCLC responds well to chemotherapy and radiotherapy treatment initially. However, less than 5 percent of SCLC patients survive five years past diagnosis; a patient with untreated SCLC has an average survival time of two to three months (Toyooka S et al 2001).
Mesothelioma. Mesothelioma is diagnosed when cancer cells are found in pleural fluid or tissue. It is associated with asbestos exposure (70 percent of cases), and asbestos workers have a lifetime risk of 8 percent; tumors arise 20 to 40 years after asbestos exposure. Mesothelioma has a poor prognosis, with 75 percent of patients dying within one year and five-year survival being about 5 percent. Long-term survival has been reported in 50 percent of patients who receive a combination of surgical removal of cancer followed by chemotherapy during surgery and intraperitoneal chemotherapy soon after surgery.