Recurring inflammations of the lung (tuberculosis or pneumonia) leave scarring of the tissue and the scar tissue is a risk factor for some type of lung cancer.
Radiation therapy to the chest, air pollution, exposure to different cancer causing agents at working place and their deposits in the soil in our environment increase the risk for developing lung cancer.

A study completed in 2006 shows no increase in lung cancer for marijuana smokers, even those who had smoked heavily. The researcher, Dr. Donald Tashkin had previously published anti-marijuana reports, but did not find an association between use of cannabis and lung cancer. http://www.washingtonpost.com/wp-dyn/conte nt/article/2006/05/25/AR2006052501729.html If you want more information on the topic of marijuana and cancer please visit http://www.safeaccessnow.org If you find information useful to other patients, please come back and share the info with us.