It usually begins along the outer edges of the lungs and under the lining of the bronchi. Large cell carcinomas are a group of cancer with large abnormal looking cells. These tumors usually begin along the outer edges of the lung. Developing slowly, its symptoms can go undetected for as long as 10 to 20 years. Incidence is declining significantly in men from 86.5 per 100,000 in 1984 to 70 per 100,000 in 1996.
Cigarette smoking is the leading risk factor in the development of lung cancer.
Up to 90 percent of lung cancer is caused by smoking. Currently 48 million adults are smokers, with men being more likely to smoke than women. Occupations with exposure to hazardous agents. Exposure to chemical products. A scarred area of the lung caused by a prior inflammation.