Surgery for Rectal Carcinoma - Continued (page 2 of 4)
By David S. Medich, M.D.
Director, Division of Colon and Rectal Surgery

Surgical Options/Definitions
The surgical management of rectal carcinoma is dependant on multiple variables and is controversial, even when keeping in mind the uncompromising principal of en bloc resection of the tumor and its lymphvascular pedicle. These variables include location of the tumor defined as distance from the pelvic floor as well as circumferential orientation, clinical stage and surgeon experience. The surgical management of tumors that arise from the proximal rectum is the least controversial and will not be discussed in detail. The standard of care throughout the world is resection of the proximal rectum and sigmoid colon with colo-rectal anastomosis (CRA), commonly known as low anterior resection (LAR).

To avoid confusion, we refer to LAR when the tumor arises from the intraperitoneal portion of the rectum, and the CRA is made to the retroperitoneal portion of the rectum. A significant reservoir of rectum above the pelvic floor remains. We approach management issues with these patients the same way we approach patients with colon carcinoma. Tumors that arise from the mid/distal portion of the rectum present an anatomic challenge and result in higher LR rates and more complicated functional concerns. In these patients, anterior resection results in complete removal of the rectal reservoir above the pelvic floor. We refer to this as proctosigmoidectomy followed by whatever restorative procedure follows (e.g. proctosigmoidectomy with colonic J-pouch anal anastomosis). Others refer to anterior resection to include all resections of rectal carcinoma done from an anterior (transperitoneal) approach, regardless of whether any residual rectal reservoir remains. Abdominal-perineal resection (APR) includes removal of the surgical anal canal en bloc with proctosigmoidectomy. It should be noted that the anterior portion of an APR is identical to proctosigmoidectomy with restorative intent. Therefore, the anal canal only needs to be removed when tumor margin cannot otherwise be obtained.

The approach to tumors that arise from the mid/distal (retroperitoneal) rectum is dependent mostly on the clinical stage of the lesion and the surgeon’s training and experience. We perform endorectal ultrasound as well as CT of the thorax, abdomen and pelvis to clinically stage all such patients. If it can be anticipated that a tumorfree margin can be obtained by anterior resection, then a sphincter-preserving procedure is planned. With removal of the entire rectal reservoir, the surgeon has the option of performing a straight colo-anal anastomosis (CAA) or creating a reservoir, usually a colonic J-pouch. A colonic J-pouch anal anastomosis (CJAA) is created by joining the antimesenteric portion of the descending colon to create a reservoir and making an anastomosis to the top of the anal canal. (See Figure 1) Most studies have shown improved functional outcome compared to a straight CAA with the patients experiencing less frequent bowel movements, improved continence and less rectal urgency. We have performed nearly 200 of these procedures at AGH with approximately 90 percent of the patients being satisfied or greatly satisfied with the functional outcome. The length of gross distal margin necessary to secure microscopic negative margins is 2 cm in greater than 90 percent of cases, and any length in the patient who has undergone chemoradiotherapy (CRT) preoperatively. Therefore, most patients with rectal carcinoma are candidates for sphincter preservation. At AGH, patients with cT3-4 rectal tumors are treated routinely with neoadjuvant CRT allowing a minimal distal margin.