Mayo Clinic News Network DEAR MAYO CLINIC: I am 62 and recently had a physical. My doctor suggested that I should be screened for lung cancer. I used to smoke a pack of cigarettes a day but quit about a decade ago. I’ve not had any problems, so I’m wondering if this is necessary. What does screening involve? ANSWER: More than 600,000 people die annually from cancer in the U.S. Lung cancer…