Histologic and Immunochemical Assessment of Colorectal Cancers

<h3>ABSTRACT</h3> Traditional assessment of colorectal cancer includes gross anatomy, routine histology, special stains, and immunohistochemistry. Newer methods, including molecular techniques, can better predict recurrence potential and directed treatments. Distinction of benign versus malignant neoplasms leads to a series of additional tests that are useful in guiding diagnosis, prognosis, and treatment. In this article, we focus on the histological assessment of grade and stage of the tumor, utilizing the College of American Pathologists and the American Society for Clinical Oncology guidelines. We then discuss the definition and utility of cancer staging in the determination of treatment. The 5-year median survival rate estimate is based on these staging principles; thus, practitioners utilize this system to develop a precise treatment plan taking individual patient variables into consideration. Screening of the patient for specific tumor markers from the serum or on the excised neoplasm further helps elucidate cancer subtype and therapy. Markers, such as carcinoembryonic antigen C-reactive protein in the serum as well as numerous immunohistochemical markers, are utilized for this purpose. Finally, we examine Lynch syndrome, mismatch repair proteins, and microsatellite instability as additional markers and potential treatment targets.