Lung Cancer
Lung cancer occurs when lung tissue develops cancerous growths. Primary lung cancer is cancer that originates in the lung tissue. Secondary lung cancer is cancer that spreads, or metastasizes, from other organs.
Primary Lung Cancer
There are several different types of primary lung cancer. The two main groups of primary lung cancer are small cell and non-small cell lung cancer. Pleural mesothelioma is often thought of as a third type of primary lung cancer. However, it is not a lung cancer. Malignant mesothelioma does not develop in the lungs, but in the serous membranes surrounding the lungs. Therefore, it does not fall into the typical categories of lung cancer. Malignant mesothelioma can also occur in other tissues, in the lining of the abdomen, called peritoneal mesothelioma, and in the lining of the heart, known as pericardial mesothelioma.
Small Cell Lung Cancer
Small cell lung cancer makes up approximately twenty percent of the primary types of lung cancer. It is called small cell cancer because the tumor cells are very small. The cells contain almost exclusively the cell nucleus and nothing more. This type of cancer is also referred to as "oat cell" cancer. Chemotherapy is generally suggested for this cancer in the early stages due to the rapid way it which it spreads. Surgery is not considered a good option to stop the spread early on. This type of cancer is most closely linked to smoking; non-smokers rarely have it.
Non-Small Cell Cancer
There are five categories and each category of non-small cell cancer are physiologically similar. They respond to treatment differently than small cell lung cancer does.
Squamous cell carcinoma is a common type of primary lung cancer. This type of cancer is also related to smoking and it emerges from the cells than line the airways in the lungs. Squamous cells are thin, flat cells that look like fish scales. Commonly the tumor growths are located in the middle of the lungs near the bronchi. It is also referred to as epidermoid carcinoma. It made up of approximately 30 to 35% of the non-small cell cancer in the U.S., which affects men and the elderly most frequently.
Adenocarcinoma, like squamous cell carcinoma, develops from tissues in the lung airways. However, it develops from the glandular secretory tissues. It is often found in the outer airway passages like the squamous cell variety. The number of cases of this cancer is increasing. It comprises about 40% of the non-small cell lung cancer in the U.S. and is the most common lung cancer among women.
Large cell lung cancer is named after its appearance. The cells appear large and unnatural under the microscope. These types of cells grow very quickly.
Adenosquamous carcinoma are cells that appear flat under the microscope, similar to the squamous cells, but come from the glandular secretory cells, like the adenocarcinoma.
Undifferentiated carcinoma includes cancer cells that cannot be identified as one of the other groups. These cells appear abnormal under the microscope and multiply uncontrollably.
Secondary Lung Cancer
Secondary lung cancer spreads to the lungs from other organs. Many different types of cancer spread to the lungs because of its very high blood supply. These include breast cancer and colon cancer.
Knowing the type of cancer is crucial when it comes to treatment. The different types of cancer cells respond differently to different types of chemotherapy and other therapies. When cancer cells spread from other organs to the lungs, the lungs have to be treated for the other type of cancer, not lung cancer. This is an important distinction. For example, breast cancer that spreads to the lungs is treated as breast cancer, not lung cancer.
For more on mesothelioma information click here.