Colorectal Cancer and Ostomy Surgery

Colorectal cancer — cancer arising in the colon or rectum — is the fourth most common cancer in the United Kingdom and a leading cause of cancer-related mortality worldwide. For a significant proportion of people diagnosed with this condition, surgery forms the cornerstone of treatment, and that surgery may involve the formation of a stoma: an opening on the abdominal wall through which waste leaves the body. Understanding why a stoma may be necessary, which type is most likely, and what the journey from diagnosis to recovery involves can help patients and their families feel better prepared.

Why Colorectal Cancer May Require a Stoma

Not every person with colorectal cancer will need a stoma, but several circumstances make one necessary or advisable.

Tumour Location

The position of a tumour within the bowel is the most important factor. Cancers of the sigmoid colon or upper rectum can often be removed and the bowel rejoined (anastomosed) without a permanent stoma, though a temporary one may be used to protect the join while it heals. Cancers of the lower rectum, particularly those close to or involving the anal sphincter muscles, frequently require removal of the sphincter itself — a procedure called abdominoperineal resection (APR) — which results in a permanent end colostomy.

Emergency Presentation

Approximately 20–30% of colorectal cancers present as emergencies, most commonly with bowel obstruction or perforation. Emergency surgery carries a higher risk of complications, and forming a stoma rather than attempting an immediate anastomosis is often the safest approach. These stomas may later be reversed once the patient has recovered and, if appropriate, received further treatment.

Stage of Disease

Locally advanced tumours that have grown into surrounding structures, or cases where the bowel has perforated and caused peritonitis, may require more extensive resection that makes immediate bowel continuity impossible or unsafe.

Types of Stoma Formed in Colorectal Cancer Surgery

End Colostomy

An end colostomy is the most common permanent stoma associated with colorectal cancer. It is formed from the descending or sigmoid colon and produces semi-formed to formed stool, usually once or twice a day. It sits on the left side of the abdomen in most cases and is managed with a closed or drainable pouch.

Loop or End Ileostomy

An ileostomy — opening onto the small bowel — is used when a low rectal anastomosis needs protection, or when large sections of colon have been removed. Output is liquid to porridge-like consistency, and the stoma is typically sited on the right side. A loop ileostomy (where a loop of bowel is brought through the abdominal wall with two openings) is the most common form of temporary, defunctioning stoma after rectal cancer surgery.

Loop Colostomy

A loop colostomy may be formed as a palliative measure in patients whose tumour cannot be removed but is causing obstruction, diverting the faecal stream to relieve symptoms and improve quality of life.

Surgical Procedures Commonly Involved

• Anterior resection: Removal of part of the rectum with restoration of bowel continuity; often accompanied by a temporary loop ileostomy.
• Low anterior resection (LAR): For tumours in the lower rectum; a protective ileostomy is almost always recommended given the technical difficulty and risk of anastomotic leak.
• Abdominoperineal resection (APR): Removal of the rectum, anus, and sphincter complex; always results in a permanent end colostomy.
• Hartmann’s procedure: Removal of the sigmoid colon or rectum with formation of an end colostomy and closure of the rectal stump; may be reversed at a later date.
• Subtotal or total colectomy: Removal of most or all of the large bowel, sometimes required for obstructing right-sided cancers or hereditary conditions predisposing to colorectal cancer.

Before Surgery: Preparation and Stoma Siting

Pre-operative assessment by a specialist stoma care nurse (SCN) or wound, ostomy and continence nurse is considered best practice and is recommended by international guidelines. At this appointment the nurse will:

• Mark the optimal stoma site on the abdomen, taking into account skin folds, the belt line, bony prominences, and daily activities.
• Explain what the stoma will look like and how it functions.
• Address concerns and begin psychological preparation.

If neoadjuvant chemoradiotherapy is planned before surgery, siting is still carried out in advance to inform the surgical approach.

Recovery and Living With a Stoma After Cancer Treatment

The Early Post-operative Period

In the first days after surgery, the stoma care nurse supervises pouch changes and begins teaching self-care. The stoma is typically oedematous (swollen) in the early weeks and will reduce in size over six to eight weeks, after which a definitive pouching system can be selected.

Ongoing Cancer Treatment

Many patients require adjuvant chemotherapy after surgery. Chemotherapy can cause nausea, diarrhoea, and altered stoma output. The stoma care nurse works alongside the oncology team to manage these side effects and adapt the pouching system accordingly. Radiotherapy to the pelvis, whether given before or after surgery, can cause skin sensitivity around the stoma and in the perineal area, requiring careful skin care.

Psychological and Quality-of-Life Considerations

Body image concerns, anxiety about pouch management, and changes to sexual function and continence are well-recognised challenges following colorectal cancer surgery and stoma formation. Structured nurse-led education, peer support through ostomy associations, and psychological referral where needed have all been shown to improve adjustment and quality of life.

Stoma Reversal

For patients with a temporary stoma, reversal is usually planned three to twelve months after the original operation, provided imaging confirms the anastomosis has healed and the patient is fit for surgery. Discussion about the realistic likelihood and timing of reversal should happen before the initial operation.

Palliative and End-of-Life Stoma Care

In advanced or metastatic colorectal cancer, a stoma may be formed purely to relieve obstruction and improve comfort. In this context, the goals of care shift towards symptom management, and the stoma care nurse plays a central role in ensuring that pouch management remains practical and dignified as the patient’s functional status changes.

The Bottom Line

Colorectal cancer surgery and stoma formation are deeply intertwined for a substantial number of patients. Whether a stoma is temporary or permanent, planned or emergency, depends on tumour biology, surgical technique, and individual patient factors. With skilled pre- and post-operative support from a specialist stoma care nurse, most people adapt successfully and maintain a good quality of life. Anyone facing colorectal cancer surgery should receive a dedicated pre-operative stoma care consultation and have access to ongoing specialist nurse support throughout treatment and beyond. Always discuss your individual circumstances with your surgeon and stoma care nurse.