Smoking and exposure to smoke can cause small cell carcinoma. Along with family history of lung cancer. If you have already had cancer in your chest or breast area, the radiation can cause small cell carcinoma. In a work environment that has had asbestos, chromium, nickel, arsenic, soot, or tar increases your chances of small cell carcinoma. If you are HIV positive or live in pollution it can increase the risk chances as well.

How it is contracted!