Background/Aims: Non-radical primary tumour resection (PTR) of asymptomatic metastatic colorectal cancer (mCRC) can prolong survival time of some patients. Patients with mutated RAS gene have worse survival outcome. This study aimed to investigate the impact of RAS gene mutations on the prognosis of asymptomatic unresectable mCRC patients who underwent PTR. Methods: A retrospective observational cohort study was deduced among mCRC patients who experienced PTR or had intact primary tumour (IPT). All of them had the primary tumour tissue genotyping tested for RAS (KRAS and NRAS) gene mutations. The tumour-related overall survival (OS) time and progression-free survival (PFS) time was estimated. From January 2011 to June 2014, 421 mCRC patients with asymptomatic, unresectable, metastatic disease were enrolled in this study. Among them, 282 patients underwent PTR and 139 patients had IPT. Results: The mutation rate of RAS was 53.8% (221/411). With a median followed-up time of 46.5 months, the overall survival time of mCRC patients harboring wtRAS or mtRAS was 28.0 versus 22.0 months (p = 0.043) in PTR group and was 21.6 versus 17.8 months (p=0.071) in IPT groups. A Multivariate regression analysis suggested that RAS gene (p=0.039, HR=1.288,95%CI [1.072∼2.911]), metastatic organ number (p=0.033, HR=3.091,95%CI [1.090∼5.755]) and systemic therapy response (p=0.019, HR=0.622,95%CI [0.525∼0.811]) were independent prognostic factors in PTR population. Conclusion: We found that wild-type RAS gene was a favorable factor for the asymptomatic unresectable mCRC patients experiencing PTR.
418P Upfront primary tumour resection (UPTR) and survival in synchronous metastatic colorectal cancer according to primary tumour location and RAS status: Pooled analysis of the Spanish Cooperative Group for the Treatment of Digestive Tumours (TTD)
