KRAS and neoplasm: Initially, archival tumor samples were analyzed by Sanger sequencing for mutations in KIT, PDGFRA, BRAF, and KRAS. A KIT mutation was identified in 67% (68/102) of tumor samples acceptable for analysis (≥ 50% tumor cells); 61% (62/102) had primary mutations, 12% (12/102) had secondary mutations, and 33% (34/102) were KIT wild type.