A randomized placebo-controlled trial of erlotinib in patients with advanced non-small cell lung cancer (NSCLC) following failure of first-line or second-line chemotherapy: a National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) trial [abstract 7022] - Shepherd,F.; Pereira,J.; Ciuleanu,T.E. (Proc Am Soc Clin Oncol, 2004)