From the American Cancer Society's Annual Report!!

"An estimated 577,190 people will die from cancer in 2012, according to the report.  Nearly 175,000 of those deaths--about a third--will be due to tobacco use alone.  And additional one-third of cancer deaths will be caused by obesity and overweight, lack of physical activity and poor diet, the organization says."

Harvard Women's Health Watch, July 2012

What more do you need to know?