Molecular Characterization Of Colorectal Tumors In Young Patients Compared With Older Patients And Impact On Outcome.

505 Background: The incidence of colorectal cancer (CRC) among young individuals is rising. The effect of an individual’s age on their tumor molecular profile is unknown. Methods: Molecular profiles of 4,821 tumors obtained from younger and older CRC patients (pts) were reviewed and correlated with pt outcome. Protein expression (IHC), gene amplification (ISH), sequencing (NGS and Sanger), and fragment analysis were performed. T and Fisher’s exact tests determined differences between age groups; Kaplan-Meier methodology estimated survival. Results: Tumors from 1,277 younger (median age 40; range 15-45 yr) and 3,544 older (72; 65-98) pts were studied. Most frequently mutated genes included TP53, APC, KRAS, PIK3CA, SMAD4, and BRCA1/2. Mutation rates for BRAF (14.4% vs. 4.8%, p u003c 0.001), APC (62% vs. 54%, p = 0.0034), FBXW7 (9.6% vs. 5.5%, p = 0.01), and KRAS (45% vs. 41%, p = 0.02) were higher in older pts; NRAS mutation rates (4.5% vs. 3.9%) were similar in both groups. Younger pts had higher overexpressio...