Pathological evaluation of colorectal cancer specimens: advanced and early lesions

Surgical resection is the treatment of choice for patients with locally confined disease, but early cancers may be adequately treated by endoscopic resection alone. In advanced colorectal cancers, accurate staging including pathological lymph node assessment is crucial for patient counselling and decision making. In addition to the extent of surgical lymph node removal and the thoroughness of the pathologist in dissecting the cancer specimen lymph node recovery is related to the actual number of regional lymph nodes that is related to patient demographics, tumor location and biology. Current guidelines recommend a minimum of twelve nodes harvested as the standard of care. In patients with node-negative tumors a variety of histological features may be used for adjusted risk assessment, including histological subtyping, lymphatic and venous invasion, tumor budding and tumor necrosis as well as the anti-tumor host inflammatory response which has been identified as favorable feature in several studies. In rectal cancer, involvement of the circumferential resection margin and the plane of surgery are important prognostic factors. Early or superficial colorectal cancer is defined as invasive adenocarcinoma invading into, but not beyond the submucosa. A number of features require special attention because they are used to determine the necessity for radical surgery. In addition to the assessment of completeness of excision, these include the recording of parameters that predict the presence of lymph node metastasis, namely the depth of invasion into the submucosa, tumor grade, and the presence of additional risk factors, such as angioinvasion and tumor budding. The combination of these parameters allows the stratification of affected individuals into low-risk and high-risk categories.