Predictive factors to targeted treatment in gastrointestinal carcinomas.

Most cancers are traditionally treated with either chemotherapeutic agents, radiotherapy, or both. Identification of specific molecular characteristics of tumors and the advent of molecular-targeted drugs not only enhance the efficacy but also decrease the toxicity of treatment. These new therapies may target pathways critical to tumor development or specific driver mutations in cancer cells. This understanding of the molecular pathways of cancer cells has led to the ability to predict cancer development, behaviour and prognosis, as well as response or resistance to current therapeutic agents. As a result, pathologic analyses play a vital role in the detection of cancer biomarkers, which are important not only in the diagnosis of cancers but also in the selection of appropriate therapeutic agents and in the development of new targeted therapies.