Pre-operative staging of rectal neoplasm and its impact on clinical management.

A sophisticated staging technique (extended staging, ES) employing modern technology has been compared prospectively with conventional clinical assessment (initial staging, IS) in 45 patients with low rectal carcinoma (less than 12 cm from the anal verge) to determine its potential merit and its impact on clinical management. ES consisted of computerized tomography of liver and pelvis, ultrasound scan of liver, measurement of serum concentrations of carcinoembryonic antigen (CEA) and acute phase reactant proteins and multiple superficial and deep biopsies to determine not only the histological grade of the tumour but also its DNA cellular content as measured by flow cytometry. ES proved statistically superior to IS in the assessment of local spread and dissemination. Although histological grade proved to be more accurate on ES than IS this was only true when one specialist pathologist interpreted the slides. When several pathologists were involved interobserver variation made interpretation unreliable. Assessment of DNA content using flow cytometry, being quantitative, was more accurate and perhaps should be used in the future as a prognostic indicator. The improved accuracy of ES would have altered both pre- and intra-operative clinical decisions. It would have prevented some patients receiving inappropriate adjuvant therapy as well as selecting patients more accurately for the correct treatment.