Adjuvant chemotherapy (ACT) in stage II colon cancer (CC) in patients with Lynch syndrome.

3550 Background: Previous studies showed conflicting results regarding the value of ACT in MSI-H CC. A recent study reported differential benefits from 5-FU-based ACT comparing suspected sporadic vs suspected hereditary MSI-H CC. We sought to evaluate the prognostic impact of ACT in a large cohort of Lynch syndrome (LS) patients (pts) with stage II CC. Methods: To minimize selection bias diagnoses >2 years prior to registration in the database of the German HNPCC consortium were excluded. 278 patients (61% male, mean age 42.9y, 13% stage IIB, 51% with MMR gene mutation) were eligible. Overall Survival (OS), CC-specific Survival (CSS), and Disease Free Survival (DFS) were analyzed using Kaplan-Meier and Cox Regression analyses. Results: 5y OS, CSS and DFS were 95%, 95% and 93% respectively. Right-sided CC was independently associated with lower DFS in stage II and IIA. Increasing age was associated with lower OS, CSS and DFS in stage IIA, however we observed only trends in the multivariate analysis. Surger...