Characteristics of Mutant, Deficient Mismatch Repair/Proficient Mismatch Repair, Metastatic Colorectal Cancer: A Multicenter Series of 287 Patients.

BACKGROUND

mutations occurring in about 10% of metastatic colorectal cancers (mCRCs) are usually associated with a poor outcome. However, their prognostic factors are unknown.

MATERIALS AND METHODS

We built a multicenter clinico-biological database gathering data from patients with -mutant mCRC treated in one of the 16 French centers from 2006 to 2017. The primary endpoint was to identify prognostic factors using a Cox model.

RESULTS

We included 287 patients (median age, 67 years [28-95]; female, 57%). Their median overall survival was 20.8 months (95% confidence interval [CI], 17.97-27.04), and median progression-free survival in the first-line setting was 4.34 months (95% CI, 3.81-5.03). Chemotherapy regimen and biological agents (antiangiogenic or anti-epidermal growth factor receptor) were not associated with overall and progression-free survival. Stage IV disease (synchronous metastases) and absence of curative-intent surgery were statistically associated with poor overall survival. Among the 194 patients with mismatch repair (MMR) status available, overall survival was significantly longer in patients with deficient MMR tumors compared with those with proficient MMR tumors (adjusted hazard ratio = 0.56; = .009).

CONCLUSION

Despite that -mutant mCRCs are associated with poor overall and progression-free-survival, patients with deficient MMR tumors and/or resectable disease experienced a longer survival. These results highlight the importance of MMR testing and resectability discussion in patients with mCRC in day-to-day practice.

IMPLICATIONS FOR PRACTICE

Mismatch repair (MMR) testing and resectability discussion in patients with metastatic colorectal cancer (mCRC) should be performed in day-to-day practice to steer treatment decision making in patients with -mutant mCRC.