The term lung cancer is used for tumors arising from the respiratory epithelium (bronchi, bronchioles, and alveoli). Mesotheliomas, lymphomas, and stromal tumors (sarcomas) are distinct from epithelial lung cancer.INTRODUCTION:The incidence of lung cancer peaks between ages 55 and 65 years. Lung cancer accounts for 29% of all cancer deaths ,31% in men, 26% in women. Lung cancer is responsible for more deaths each year than breast cancer, colon cancer, and prostate cancer combined; more women die each year of lung cancer than of breast cancer. The age-adjusted lung cancer death rate in males is decreasing, but in females it is stable or still increasing. These death rates are related to smoking; smoking cessation efforts begun 40 years ago in men are largely responsible for the change in incidence and death rates. Thus, primary carcinoma of the lung is a major health problem with a generally grim prognosis.PathologyFour major cell types make up 88% of all primary lung neoplasms according to the World Health Organization classification .These are squamous or epidermoid carcinoma, small cell also called oat cell carcinoma, adeno carcinoma including bronchioloalveolar, and large cell carcinoma.EtiologyMost lung cancers are caused by carcinogens and tumor promoters inhaled via cigarette smoking. The relative risk of developing lung cancer is increased about thirteen fold by active smoking and about 1.5-fold by long-term passive exposure to cigarette smoke. Chronic obstructive pulmonary disease, which is also smoking-related, further increases the risk of developing lung cancer. The lung cancer death rate is related to the total amount often expressed in "cigarette pack-years" of cigarettes smoked, such that the risk is increased 60- to 70-fold for a man smoking two packs a day for 20 years as compared with a non smoker. The chance of developing lung cancer decreases with cessation of smoking but may never return to the nonsmoker level. The increase in lung cancer rate in women is also associated with a rise in cigarette smoking. Women have a higher relative risk per given exposure than men .This sex difference may be due to a greater susceptibility to tobacco carcinogens in women, although the data are controversial.The reason for this sex difference is not known but may be related to hormonal factors.Preventing people from starting to smoke is thus very important, and this primary prevention effort needs to be targeted to children since most cigarette smoking addiction occurs during the teenage years.Radiation is another environmental cause of lung cancer. People exposed to high levels of radon or receiving thoracic radiation therapy have a higher than normal incidence of lung cancer, particularly if they smoke. The treatment is may be by the chemotheray agent or by surgery or by the radiation therapy. The disease cannot be cured but the spreading can be controlled by the meditation.
