Tobacco use negatively affects every system in your body. We've all learned to associate smoking with lung cancer and emphysema, but it causes many more diseases. Smoking can directly lead to heart disease and stroke along with asthma, hypertension and cancer in any part of your body. According to the Centers for Disease Control and Prevention (CDC), cigarette smoking causes approximately 1 in 5 deaths every year and it's the leading cause of preventable deaths in the United States.