P-251The prognostic ad predictive value of primary tumor sidedness in the mCRC pts

Introduction: The prognostic and predictive value of primary tumor sidedness in the pts with metastatic colorectal cancer (mCRC) is well known today. Right-sided primary was associated with high mutational burden, microsatellite instability, worse prognosis, more BRAF mutation rates and poor anti-EGFR response. We aimed to investigate the effects of tumor sidedness on survival, RAS-RAF mutation rates and responses to biologic agents in the pts with mCRC.