Minimally invasive biomarkers for detection and staging of colorectal cancer

Colorectal cancer (CRC) is the third most prevalent cancer, with approximately one million cases estimated world wide in 2006, resulting in more than 500,000 deaths. Approximately 40% of colorectal cancers are diagnosed with localized disease, which have approximately a 90% five-year survival rate. However, the prognosis worsens with advancing stage, and only 5% of patients diagnosed with distant metastases survive 5 years. Therefore, the need for early detection is clear. Currently, guaiac-based fecal-occult blood testing (gFOBT) in large population-based trials has been shown to reduce CRC-related mortality, but the sensitivity for detecting early disease is low. DNA-based fecal screening appears to have the potential to significantly increase sensitivity without decreasing specificity. This review will focus primarily on newer molecular-based biomarkers and their utility in screening large populations for CRC, predicting treatment efficacy and providing prognostic information related to survival and disease progression.