10 of the Worst Diseases Smoking Causes Smoking cigarettes will kill you, but before you die, you could experience some pretty terrible diseases and health conditions from smoking. Here are some of the most gruesome diseases caused by smoking*: Lung Cancer More people die from lung cancer than any other type of cancer. Cigarette smoking is the number one risk factor for lung cancer; it's responsible for 87 percent of lung cancer deaths. Your chance of still being alive five years after being diagnosed is less than 1 in 5. COPD (chronic obstructive pulmonary disease) COPD is an obstructive lung disease that makes it hard to breathe . It causes serious long-term disability and early death. COPD starts by making it hard to be active, such as playing with a grandchild, then usually gets worse, until climbing a short set of stairs or even walking to get the mail is exhausting or impossible. It can leave people stuck in their homes, unable to do the th...