Detection and significance of minimal residual disease in colorectal cancer

Colorectal cancer (CRC) is one of the most common causes of cancer death in the developed world. Although the primary treatment for CRC is surgical, d isease relapse due to minimal residual disease (MRD) following apparently c urative surgery occurs in up to fifty percent of patients. Most patients wh o develop overt metastases beyond the regional lymph nodes eventually die o f the disease. At present adjuvant chemotherapy is used to improve survival in patients with metastases to regional lymph nodes demonstrated by routin e histopathology with no other evidence of spread. The ability to identify metastatic disease at an earlier stage could be of considerable benefit in directing adjuvant therapy to patients at high risk of relapse who are not identified by current methods. Several techniques have been developed for t he detection of MRD, including immunohistochemical and molecular methods, h owever their role in clinical practise is not yet established. The purpose of this paper is to review these techniques and their potential clinical us e in the management of CRC.