World Lung Cancer Day was recognized on August 1, to raise awareness about the leading cause of cancer deaths worldwide. Lung cancer accounts for 12% of new cancer cases annually in the U.S., and more than 21% of all cancer deaths this year will be attributable to lung cancer, according to National Cancer Institute estimates.

People who smoke have the greatest risk of developing lung cancer, but it can occur in people who don't smoke, as well. One of the challenges is that lung cancer is often diagnosed at an advanced stage.

"Unfortunately, when tumors grow within our lungs, it's not something that our bodies can sense or feel," says Dr. Aaron Mansfield, a Mayo Clinic medical oncologist. "So we miss it at its earliest stages, unless we're doing screening. For more than half the patients, lung cancer presents when it is already metastatic."

Research has shown that lung cancer screening can detect cancer at an earlier stage and reduce the risk of dying from lung cancer.

"Right now, this screening is recommended for people who are at higher risk based on their age and smoking history," says Dr. Mansfield.

On the Mayo Clinic Q&A podcast, Dr. Mansfield, discusses screening, diagnosis and treatment for lung cancer.