Genomic alterations associated with early-stage disease and early recurrence in patients with colorectal cancer.

Background: The molecular characterization of early-stage (1-3) colorectal cancer (CRC) remains incomplete, as opposed to metastatic disease, where comprehensive genomic profiling (CGP) is routinely performed. This study aimed to characterize the genomics of stages 1-3 versus IV CRC, and the genomics of patients recurring within 1 year of diagnosis.

Patients and methods: Patients from a de-identified CRC clinico-genomic database who received Foundation Medicine testing (FoundationOne/FoundationOne CDx) during routine clinical care at approximately 280 US cancer clinics between March 2014 and June 2023 were included. Genomic alterations (GA) were compared by Fisher's exact test.

Results: A total of 4702 patients were included; 1902 with stages 1-3 and 2800 with stage 4 disease. Among patients with stages 1-3 disease, 546 recurred within 1 year. Patients staged 1-3 had higher prevalence of microsatellite instability (MSI-H, 11.4% vs 4.5%, P < .001), tumor mutational burden (TMB) ≥ 10 Mut/Mb (14.6% vs 6.8%, P < .001), GA in RNF43 (11.2% vs 5.7%, P < .001), MSH6 (3.9% vs 1.7%, P < .001), MLH1 (2.3% vs 0.7%, P < .001), and MSH2 (1.5% vs 0.6%, P < .01) compared to those with stage 4 disease. Patients who recurred within 1 year had higher prevalence of MSI-H (13.2% vs 4.4%, P < .001), TMB ≥ 10 Mut/Mb (16.2% vs 6.9%, P < .001), BRAF V600E (17.2% vs 7.9%, P < .003), GA in RNF43 (13.7% vs 5.3%, P < .001), MSH6 (4.2% vs 1.6%, P = .035), and BRCA1/2 (6.2% vs 3.0%, P = .030). On recurrence, more patients received targeted therapy when CGP was performed before versus after first-line therapy (43% vs 19%, P < .001).

Conclusions: Early-stage CRC patients can have distinct genomic profiles and CGP in this population can help expand access to targeted therapies.