The influence of microsatellite instability and other biomarkers in clinical outcomes of patients with advanced colorectal cancer: a case control study

Abstract

This is a clinical case-control study to assess whether the presence of some biomarkers, such as microsatellite instability (MSI), KRAS and BRAF mutations impact on the response rate, progression-free survival and overall survival in patients with metastatic colorectal cancer (mCRC) who underwent chemotherapy treatment based on oxaliplatin or irinotecano. The cases are patients with mCRC and the presence of instability high degree of microsatellite (MSI-H) and the controls are those with microsatellite stability or instability of low grade (MSI-L / S). Eligible patients will be identified from administrative list of Outpatient Oncology Gastrointestinal Cancer clinics ate the Institute of the State of São Paulo (ICESP), between December 2009 and January 2011. They should have received at least two months of chemotherapy until January 2011 for at least one radiological evaluation, after the baseline, has been performed in order to check whether or not there was no response to the chemotherapy regimen proposed. Despite the introduction of new drugs in the treatment of RCC, the overall survival in stage IV is still low and little is known about the impact of MSI and other biomarkers in response to treatment, especially in metastatic disease, because the search for these biomarkers are more frequent in the adjuvant treatment. Tumors with MSI tend to have better survival in early stages, however, in mCRC its prevalence is low and prognostic data are limited. MSI-H will be evaluated through immunehistochemistry and mutations status will be checked by sequencing. (AU)