CHICAGO — It's way too soon to declare success, but an experimental drug for lung cancer patients with a certain gene showed extraordinary promise in early testing, doctors reported at a cancer conference on Saturday. More than 90 percent of the 82 patients in a study saw their tumors shrink after two months on the drug, Pfizer Inc.'s crizotinib (crih-ZAH-tin-ib), researchers reported. Doctors had expected only about 10 percent of these very sick patients to respond to the drug, according to one of the study's leaders, Dr. Yung-Jue Bang