Practical and Molecular Evaluation of Colorectal Cancer: New Roles for the Pathologist in the Era of Targeted Therapy

Abstract

Abstract Context.—Colorectal cancer is the third most common cancer and the fourth most common cause of cancer death worldwide. Patient cases are discussed in multidisciplinary meetings to decide on the best management on an individual basis. Until recently, the main task of the pathologist in such teams was to provide clinically useful reports comprising staging of colorectal cancer in surgical specimens. The advent of total mesorectal excision and the application of anti-epidermal growth factor receptor (EGFR)–targeted therapies for selected patients with metastasized colorectal cancer have changed the role of the pathologist. Objectives.—To present the traditional role of the pathologist in the multidisciplinary team treating patients with colorectal cancer, to address the technique of total mesorectal excision and its implications for the evaluation of surgical specimens, to offer background information on the various EGFR-targeted therapies, and to review the currently investigated tissue biomarkers assumed to be predictive for efficacy of such therapies, with a focus on the role of the pathologist in determining the status of such biomarkers in individual tumors. Data Sources.—This article is based on selected articles pertaining to biopsy evaluation of colorectal carcinoma and reviews of EGFR-targeted therapies for this cancer. All references are accessible via the PubMed database (US National Library of Medicine and the National Institutes of Health). Conclusions.—Pathologists play an increasingly important role in the diagnosis and management of colorectal cancer because of the advent of new surgical techniques and of targeted therapies. It is expected that this role will increase further in the near future.