What are the indications for colon resection (colectomy) in patients with colorectal cancer?

Updated: Apr 05, 2021
  • Author: David E Stein, MD, MHCM; Chief Editor: Vikram Kate, FRCS, MS, MBBS, PhD, FACS, FACG, FRCS(Edin), FRCS(Glasg), FIMSA, MAMS, MASCRS, FFST(Ed)  more...
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Answer

Colorectal cancer has a lifetime incidence of 6% and is the second leading cause of cancer death in the United States. It affects slightly more men than women and is curable with surgery if caught early. A colectomy for colon cancer requires removal of the tumor-affected portion of the colon and/or rectum and adequate margins, as well as the blood supply to that segment. In the vast majority of cases, primary anastomosis is performed.

In a study that included 5139 patients, Birkett et al evaluated the benefit of elective primary colon resection (ePCR) in patients with asymptomatic colon tumors and stage IV colon cancer with liver metastases, [8]  excluding those who underwent emergency colectomy or liver-based therapy. The rate of ePCR decreased significantly over time, from 84% in 2000 to 52% in 2011. Multivariate analysis indicated that older patients and patients from rural areas were more likely to undergo ePCR, as were whites as compared with African Americans. The odds of PCR were 25% higher in high-poverty areas than in low-poverty areas.  PCR was associated with a significant survival benefit.

Cecum and ascending colon cancer

Treatment for cecum and ascending colon cancer is a right hemicolectomy, which involves removing the distal 5 cm of the terminal ileum, the cecum, the ascending colon, the hepatic flexure, the first third of the transverse colon, and associated fat and lymph nodes. By convention, the dissection includes the right branch of the middle colic artery.

Transverse colon cancer

The treatment of transverse colon cancer is controversial and depends on the location of the cancer. For proximal transverse tumors and midtransverse tumors, the authors perform a right hemicolectomy. Similarly, for distal transverse tumors, even at the splenic flexure, the authors often perform an extended right colectomy. Because the cancer cells drain proximally, it is important to remove the lymph node basin proximal to the tumor. The distal margin of resection in an extended right hemicolectomy is the proximal descending colon.

Takedown and resection of the splenic flexure is followed by an anastomosis between the ileum and the upper descending colon, with the distal limb of the anastomosis dependent on blood supply from the left colic artery. The key point is takedown and resection of the splenic flexure. It is not advisable to make an anastomosis in the region of the splenic flexure, because this region is a watershed zone. Once the middle colic artery is divided, the splenic flexure becomes entirely reliant on blood supply from the inferior mesenteric artery (IMA).

One type of operation described is a limited transverse colectomy. In this procedure, only the part of the transverse colon containing the lesion is resected, followed by anastomosis of the remaining ends. This operation would be feasible for midtransverse cancers that are strictly limited to the transverse colon (ie, the cancer does not involve either flexure). However, if too much of the transverse colon is resected, tension may prevent a safe anastomosis, necessitating mobilization of both the hepatic and the splenic flexure. In such cases, it is better to perform an extended right colectomy.

Descending colon cancer

The treatment required for descending colon cancer is a left hemicolectomy, with takedown of the splenic flexure, followed by anastomosis of the transverse colon to the upper sigmoid. Depending on the extent of the cancer, the sigmoid colon may also be resected, in which case the transverse colon would be anastomosed to the rectum.

Sigmoid colon cancer

Treatment for sigmoid colon cancer is resection of the sigmoid colon, with the descending colon anastomosed to the upper rectum.

Rectal cancer

The type of resection for rectal cancer depends on the exact location of the cancer. The two common surgical options for treating rectal cancer are LAR and APR.

If the cancer is located in the upper rectum, the cancer-affected portion of the rectum is removed, along with surrounding lymph nodes, as long as a 5-cm distal mucosal margin can be obtained. The colon is then joined to the rectal stump. A circumferential dissection that includes the fascial envelope around the rectum, termed a total mesorectal excision (TME), is imperative.

If the cancer is in the middle to lower rectum and complete TME is performed, only a 2-cm distal margin is needed. These margins are important: If the tumor is too low and a margin cannot be obtained, the sphincter complex must be removed, which requires a permanent colostomy (termed an APR).

Other terminology used includes coloanal anastomosis, intersphincteric dissection, and colonic pouches. When the entire rectum must be removed for cancer clearance, the descending colon can be sewn to the anal sphincter complex at the dentate or pectinate line; this is termed a coloanal anastomosis. If the cancer is very low, the authors often remove the internal sphincter with the specimen to obtain a better margin; this is known as an intersphincteric dissection.

The rectum acts as a reservoir for feces. When a portion of the rectum is removed, a rectal stump shorter than 6 cm may lead to problems with both continence and evacuation. Rectal stumps that are longer than 12 cm do not significantly alter function.

In cases of an LAR in which less than 6 cm of rectal stump remains, the surgeon may create a colonic pouch, often called a J pouch or coloplasty, so that the patient may achieve better continence postoperatively. A pouch is an extra reservoir to help store stool. This reservoir is created by stapling or sewing loops of colon together to make a pouch and then attaching the pouch to the anus.

Studies have shown that colonic pouches are superior to coloanal anastomosis in that a J pouch results in a decreased anastomotic leak rate, a better continence rate, better control of urgency, better control of flatus, and fewer stools per day. [9]


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