ATU Images/Getty Images(NEW YORK) -- Deaths from cancer have declined by 33% since 1991, averting 4.1 million deaths. However, more people are being diagnosed with cancer than ever before, and at an earlier age, according to a major new report from the American Cancer Society. Experts say one big reason cancer deaths have declined is due to decreases in smoking rates, as well as improved treatments and targeted therapies. Still, experts are worried about the increase in some cancers in adults 50 and under -- and say it's urgent to understand what's behind the troubling trend. Especially concer...