Impact of Driver Genetic Alterations on Survival in Metastatic Colorectal Cancer Patients from a Genetically Homogeneous Sardinian Population: A Real-World Study

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Abstract
Background: Colorectal cancer (CRC) is the third most diagnosed malignancy and the second leading cause of cancer-related mortality worldwide. Recent therapeutic advancements have significantly improved clinical management, underscoring the importance of routine molecular profiling to guide personalised treatment strategies. This study aims to evaluate the prognostic impact of main molecular alterations—including allele frequency (AF) of RAS mutations—on survival outcomes in a real-world hospital-based cohort of patients with metastatic CRC. Methods: A total of 208 consecutive patients with a histologically confirmed diagnosis of CRC and complete clinical, molecular, and survival data were retrospectively analysed. Somatic mutations in KRAS, NRAS, BRAF, and the occurrence of microsatellite instability (MSI) were assessed using pyrosequencing and real-time PCR assays, respectively, on formalin-fixed, paraffin-embedded tumour samples. Associations between mutational status, clinicopathological parameters, and overall survival (OS) were evaluated. Results: Overall, 138 patients (66.3%) harboured at least one somatic mutation: 115 (55.3%) in KRAS, 8 (3.8%) in NRAS, and 15 (7.2%) in BRAF. MSI was detected in 17/208 (8.2%) patients. A statistically significant improvement in OS was observed in patients lacking mutations in any of the three genes—referred to as wild-type (WT) patients—with BRAF mutated cases showing the worst survival (p = 0.041). Increasing age at the time of first-line therapy for advanced disease stage was associated with a statistically significant increase in the hazard of death (p = 0.031). Conclusions: In the advanced disease stage, RAS/BRAF wild-type colorectal cancers were significantly associated with a survival advantage.
Funding Information
  • Sardinian Regional Government

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