Bowel Obstruction (Ileus) in Colon and Rectal Cancer: Symptoms and Treatment

Colon and rectal (large bowel / colorectal) cancerpatients may be diagnosed with various symptoms: iron deficiency anemia, rectal bleeding, changes in bowel habits, abdominal pain, palpable rectal or abdominal masses, or no signs/complaints.

However, excessive tumor growth may cause acute obstruction, with cancerous tissue completely blocking the colon lumen. Medically, this is called bowel obstruction or ileus . Patients may present with peritonitis (inflammation of the peritoneum), severe abdominal pain, swelling/tightness, absent bowel movements and constipation . Initially, small bowel obstruction may be suspected because it is more common, but 25% of all bowel obstructions occur in the colon. Of large bowel obstructions, 70% occur beyond the transverse colon, in the left colon.

Although colorectal cancers are the main cause of large bowel obstruction, other causes should be considered until diagnosis is confirmed. Patients may have other diseases causing obstruction through spread into the colon lumen, such as pancreatic or gynecological cancers (uterine, ovarian and cervical), involving metastasis . Other bowel diseases, mostly affecting the small intestine, may contribute to large bowel obstruction, such as diverticulitis, abdominal or groin radiotherapy and inflammatory bowel disease.

How is large bowel obstruction treated?

Malignant colonic obstruction can be diagnosed most quickly and easily by abdominal computed tomography (CT), which also helps identify metastatic disease. When a suspicious obstructing lesion is found, endoscopy may confirm malignancy and provide temporary decompression (opening, relief) through stenting. Patients with colorectal cancer and acute large bowel obstruction are managed by a team of oncology, gastroenterology and general surgery specialists.

Cancer-related obstruction can be surgically relieved by bringing, upstream of the obstruction, the bowel out to the skin . This surgical opening is named according to the bowel region involved; if the colon is brought to the skin, it is a colostomy, while for the small bowel it is an ileostomy or jejunostomy. Colostomy is most commonly preferred and may be temporary or permanent.

An alternative, less preferred treatment is colonic stenting. Stenting is harder or impossible when obstruction is complete, and creating a colostomy may be preferred first.

Stenting may be a temporary measure to allow surgery at an optimal time. In patients unsuitable for surgery, it may also provide a palliative solution. If considered reasonable before examination begins, fluoroscopy (a procedure guided by specialized tomography) may assist stent placement.

Both colonic stenting and surgery require caution in patients receiving the commonly used metastatic colorectal cancer drug that prevents new vessel formation, the antiangiogenic agent bevacizumab (brand name Altuzan). These patients may experience bowel perforation during stenting, bleeding during surgery and subsequent wound-healing problems.

After stent placement, patients must follow a special diet to avoid straining the stent. They should eat a low-calorie / low-fiber diet and keep stools soft with polyethylene glycol if necessary.

Colonic stents may migrate, causing obstruction-like complaints, abdominal pain and / or bloating, or rectal bleeding. Patients should know these potential complications and alert their doctor to any signs.

In summary, although not an early or common colorectal cancer symptom, large bowel obstruction is a complication to remember. CT provides diagnosis and information on tumor location. Acute obstructions are most often treated with colostomy.

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