Retrospective cohort study using the LabRx medical claims EMR database. This database contains medical claims information including diagnoses, treatments, medications, and laboratory results for 23.3 million US residents. The study cohort included adult patients (age ≥18 years) with any cancer diagnosed between October 1, 2004-June 1, 2009 who were treated with 1 one or more of the TKI agents—erlotinib, gefitinib, dasatinib, imatinib, nilotinib, or lapatinib. The index date for this cohort was the date of first administration or prescription of the TKI agent on or following the date of the first cancer diagnosis.