Biomolecular markers as determinants of patients selection for adjuvant chemotherapy of sporadic colorectal cancers

Abstract

Colorectal cancer (CRC) is a disease classified and based on genetic alteration resulting from interaction of environmental factors, individual cancer susceptibility and accumulated somatic changes of the colorectal epithelium. Advanced knowledge in genetics and epigenetics of colorectal cancer develops a hypothesis that various clinical manifestations of colorectal cancer are caused by different carcinogenesis pathways. Different carcinogenesis pathways and types of colorectal cancer appear to bring effects on different response against chemotherapy and prognosis. Chemotherapy is mainly provided for patients with stage III CRC which are also the largest proportion of CRC patients in Indonesia. However, it is also provided for some patients with high risk stage II CRC. Classically, clinical factors have been generally accepted as prognostic factors including depth of tumor invasion, regional nodal metastasis, vascular invasion, poor differentiation, and serologic tumor marker such as carcinoembryonic antigen (CEA). However, clinical and histopathological factors themselves do not provide accurate prediction for colorectal cancer prognosis and treatment. A biomolecular marker is necessary to provide such prediction. Numerous studies have been conducted to evaluate the molecular biological markers in order to determine either the possibility of successful treatment for colorectal cancer (predictive factor) or life-expectancy (prognostic factor). Results of several studies demonstrate different status of some molecular markers to determine successful treatment between stage II and stage III colorectal cancer. Certainly, such finding should be followed up but it shall be accepted that there will be a shift of paradigm of CRC treatment. Therefore, the success of colorectal cancer, excluding the patient's socioeconomic factors and the surgeon's skill, will depend extremely on molecular parameter and not only the stage.