ABSTRACT
Pathologists play a key role in the multidisciplinary team management of rectal cancer. The pathological analysis of the excised specimen provides important prognostic information on the stage of the tumour, the accuracy of radiology and the quality assurance of the surgery. Quality assurance emanates from reporting the completeness of tumour excision and the precise planes of excision, as represented by the macroscopic appearance of the specimen. The pathologist can assess the response to preoperative therapy and help to determine the need for postoperative or adjuvant therapy, either radiotherapy or chemotherapy. The pathologist can also identify patients at high risk of metachronous disease and screen for possible hereditary nonpolyposis colorectal cancer using immunohistochemistry for mismatch repair gene expression. Pathology may also help to educate radiologists and assure the quality of their reporting. More recently, pathologists have undertaken further molecular testing to help predict the type of therapy that may be effective; for example, Ki-ras mutations may be used to predict response to anti-epidermal growth factor receptor (anti-EGFr) antibodies. The current era is moving into whole-genome sequencing, which will have far-reaching implications for the diagnosis, prognosis and treatment of colorectal cancer. A further crucial responsibility is submission of high-quality pathology reports, preferably
via electronic proformas, to cancer registries so that the work of individuals, teams and institutions can be compared nationally and internationally and so that excellent and potentially suboptimal practice can be identified.
