Predictors of disease-free survival in colorectal cancer with microsatellite instability: An AGEO multicentre study

{Background: A microsatellite instability (MSI) phenotype is found in about 12% of colorectal cancers (CRCs) and is associated with a low recurrence rate after curative surgery. Several studies have identified clinical and pathological factors predictive of recurrence in resected CRC, but not in the MSI subgroup. Patients and methods: This multicentre retrospective study included patients with stage I, II or III MSI CRCs. Disease-free survival (DFS) was calculated with the Kaplan-Meier method. Factors associated with DFS were identified in univariate and multivariate Cox analyses. Results: We studied 521 patients with MSI CRC. Respectively 11%, 51% and 38% of patients were at stage I, II and III. Mean age was 68.7 years and 36% of the patients received adjuvant chemotherapy. Median follow-up was 32.8 months. The disease recurrence rates were 6% and 21% in stage II and III patients, respectively. The 3-year DFS rate was 77%. In univariate analysis, age, bowel obstruction, lymph node invasion, stage T4, vascular emboli, lymphatic invasion and perinervous invasion were associated with poorer DFS (P < 0.05). Three relevant independent predictors of poor DFS were identified in multivariate analysis, namely bowel obstruction (HR = 2.46; 95% CI 1.31-4.62