Lung Cancer
Description of Lung Cancer
Lung cancer is the malignant transformation and expansion of lung tissue, and is responsible for 1.3 million deaths worldwide annually It is the most common cause of cancer-related death in men, and the second most common in women[3]
Current research indicates that the factor with the greatest impact on risk of lung cancer is long-term exposure to inhaled carcinogens, especially tobacco smoke The occurrence of lung cancer in others (less than one tenth) appears to be due to a combination of genetic factors[6] Radon ga and air pollutio[9[10] may also contribute to the development of lung cancer.
Types
There are two main types of lung cancer categorized by the size and appearance of the malignant cells seen by a histopathologist under a microscope: non-small cell (80%) and small-cell (roughly 20%) lung cancer This classification, although based on simple histological criteria, has very important implications for clinical management and prognosis of the disease.
Non-small cell lung cancer (NSCLC)
The non-small cell lung cancers are grouped together because their prognosis and management are roughly identical. When it cannot be subtyped, it is given SNOMED code 8046/3. The subtypes are:
Squamous cell carcinoma, accounting for 29% of lung cancers also starts in the larger bronchi but grows slower. This means that the size of these tumours varies on diagnosis.
Adenocarcinoma is the most common subtype of NSCLC, accounting for 32% of lung cancers It is a form which starts near the gas-exchanging surface of the lung. Most cases of adenocarcinoma are associated with smoking. However, among people who have never smoked ("never-smokers"), adenocarcinoma is the most common form of lung cancer A subtype of adenocarcinoma, the bronchioloalveolar carcinoma, is more common in female never-smokers, and may have different responses to treatment
Large cell carcinoma is a fast-growing form, accounting for 9% of lung cancers that grows near the surface of the lung.
Small cell lung cancer (SCLC)
Small cell lung cancer (SCLC, also called "oat cell carcinoma") is the less common form of lung cancer. It tends to start in the larger breathing tubes and grows rapidly becoming quite large. The oncogene most commonly involved is L-myc. The "oat" cell contains dense neurosecretory granules which give this an endocrine/paraneoplastic syndrome association. It is initially more sensitive to chemotherapy, but ultimately carries a worse prognosis and is often metastatic at presentation. This type of lung cancer is strongly associated with smoking.
Other types
Carcinoi
Adenoid cystic carcinoma (cylindroma
Mucoepidermoid carcinom
Metastatic cancers
The lung is a common place for metastasis from tumors in other parts of the body. These cancers, however, are identified by the site of origin, e.g. a breast cancer metastasis to the lung is still known as breast cancer. The adrenal glands, liver, brain, and bone are the most common sites of metastasis from primary lung cancer itself.
Lung cancer staging
Lung cancer staging is an assessment of the degree of spread of the cancer from its original source. It is an important contributor to the prognosis and potential treatment of lung cancer.
Non-small cell lung cancer is staged from IA ("one A", best prognosis) to IV ("four", worst prognosis)
See non-small cell lung cancer staging
Small cell lung cancer is classified as limited stage if it is confined to one half of the chest and within the scope of a single radiotherapy field. Otherwise it extensive stage