[Cancer of the middle third of the rectum]

Abstract

Anterior resection and abdominoperineal resection are standard procedures to treat cancer in the upper and the lower third of the rectum, respectively. The area of interest today is the middle third of the rectum, i.e. the part 7.5-12 cm above the anal verge. Surgical therapy is mainly based on prognostic tumor factors and preoperative staging. The degree of tumor infiltration of the rectal wall and the number of positive lymph nodes are of paramount importance. For preoperative staging the results of digital examination are improved by new imaging techniques. Endorectal ultrasound is able to oklineate tumor infiltration of the rectal wall, whereas computed tomography is better suited to identify tumor infiltration outside the rectum. Preoperative lymph node staging is still not reliable. The surgeon, therefore, has to decide on the surgical therapy intraoperatively. Local tumor excision is possible only if the tumor can be reached by the finger of the surgeon, i.e. if located not more than 10 cm above the anal verge. Local excision is an acceptable procedure in high grade cancers of less than 3 cm diameter and infiltration of the muscularis propria, preferably submucosa only. Further studies are needed to evaluate the long term results. Adjuvant preoperative radiation therapy is applied increasingly in tumors infiltrating beyond the rectal wall. There is at present no apparent benefit from chemotherapy for carcinoma of the rectum.