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

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.

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.

We studied 521 patients with MSI CRC. Respectively 11%, 51% and 38% of patients were at stage I, II and III. Mean age was 68.7years and 36% of the patients received adjuvant chemotherapy. Median follow-up was 32.8months. 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, P=0.005), vascular emboli (HR=2.79; 95%CI 1.74-4.47, P<0.001) and stage T4 (HR=2.16; 95%CI 1.31-3.56, P=0.002).

Bowel obstruction, vascular emboli and stage T4 are independently associated with MSI CRC recurrence, suggesting that screening for vascular emboli in routine clinical practice may assist with adjuvant chemotherapy decision-making.