Lung cancers are broadly classified into two groups: small cell lung cancers (SCLC) and non-small cell lung cancers (NSC LC). These classifications are based on the microscopic appearance of the cells and the different ways that they grow and spread.
Small cell lung cancers (SCLC)
Approximately 20% of all lung cancers fall into this category. Small cell lung cancers are also referred to as oat cell cancers because of their appearance. The cells are only ½ to ¾ the size of NSCLC cells. A statistic worth noting is that only 1% of these cancers occur in non-smokers.
SCLC are usually centrally located and are the most aggressive of the lung cancers. This form spreads quickly and moves fast to metastasize. In many cases, evidence that the cancer has metastasized to other areas is present at the initial diagnosis.
Non-small cell lung cancers (NSCLC)
Non-small cell lung cancers are the most common primary lung cancers and are divided into three main types: adenocarcinomas, squamous cell carcinomas, and large cell carcinomas (carcinoma = cancer).
Around 50% of all NSCLC cases in the United States are adenocarcinomas. They appear in cells that form gland-like tumors on the outer edges of the lung.
Squamous cell carcinomas (cancers) are also known as epidermoid carcinomas. Squamous cells are flat cells that make up a part of the epithelium lining. They tend to appear in the central chest area and are usually slow-growing.
Large cell cancers are the least common and behave in a manner similar to adenocarcinoma.
If the lung cancer is secondary, there will most likely be multiple tumors scattered around the outside edges of the lung.