Investigating clinical and molecular characteristics of patients with PIK3CA mutation with and without KRAS mutations in colorectal cancer.

201 Background: PIK3CA mutations are some of the most common somatic mutations in colorectal cancer (CRC) and can be seen concurrently with KRAS mutations. However, it is unknown whether the presence of a concurrent KRAS mutation impacts outcomes. In this study, we investigated the clinical and molecular features of PIK3CA mutations with and without KRAS mutations, and examined the impact of KRAS mutations on clinical outcomes of patients with PIK3CA-mutated CRC. Methods: We reviewed 147 patients at our institution diagnosed with CRC cancer whose tumors harbored a pathogenic PIK3CA mutation with or without KRAS mutation. Demographic and clinical features, including age, gender, race, tumor location, and site of initial metastasis, were collected from review of electronic medical records. Fisher’s exact test was used to investigate the association between the aforementioned features and KRAS mutation status. For survival analysis, we included patients with metastatic disease (de novo or metachronous) using Kaplan-Meier survival and univariate Cox regression analysis, with statistical significance defined as a p-value threshold of