Over 90 percent of primary lung cancers begin in the bronchi, either of the two main branches of the trachea. This lung cancer is known as bronchogenic carcinoma, with the specific types being oat cell, or small cell carcinoma, adenocarcinoma, large cell carcinoma, and squamous cell carcinoma. Amongst these, the last three types are usually called non small cell lung cancers.
A subtype of adenocarcinoma, known as alveolar cell carcinoma, has its origins in the alveoli, the tiny air sacs in the lungs. Although this can develop in one part of the lung, often, it occurs simultaneously in several parts.
Some of the lung tumors that are not as common are : bronchial carcinoid, which can either be malignant or nonmalignant; sarcoma, which is cancerous; and chondromatous hamartoma, which is nonmalignant. Lymphoma is a type of cancer that affects the lymphatic system, which can have its origins in the lungs, or spread to them.
Staging of lung cancer
Non small cell lung cancer is usually staged from 1 to 4 using the TNM classification. Unlike non-small cell lung cancer, small cell lung cancer is not usually staged using TNM classification. Small cell lung cancer is staged as either limited stage disease or extensive stage disease. Small cell lung cancer patients who are having stage 1 through 3 (excluding those who have plural effusion) are staged as limited stage disease and those who have either plural effusion or metastasis disease is classified as extensive stage disease.
Staging of lung cancer is determined after determining the extent of the disease using various techniques including CT scan, MRI, PET scan and bone scan. You may read more about the imaging techniques used in lung cancer on our page dealing with on imaging techniques used in cancer.
