Bowel Cancer (Colorectal Cancer)

Bowel cancer starts in the colon or rectum and is assessed with tests that show its location and extent.

It is also known as colorectal cancer. Many bowel cancers begin in the inner lining of the bowel, sometimes from a growth called a polyp. The treatment plan is shaped by where the cancer began, how deeply it involves the bowel wall and whether it has reached other areas.

Blood in the stool and a persistent change in bowel habits are very common presentations of bowel cancer. Persistent abdominal pain, fatigue and unexplained weight loss are also common presentations. These symptoms have many possible causes, but new or ongoing changes should be assessed rather than self-treated for a long period.

Seek urgent medical advice for heavy rectal bleeding, black stools, severe abdominal swelling with vomiting, or pain that is suddenly intense. A clinician can decide whether the symptoms need same-day care and arrange appropriate tests.

Cancer develops when cells in the bowel lining acquire changes that let them multiply beyond normal control. Usually there is no single cause. Some inherited conditions, including Lynch syndrome and familial adenomatous polyposis, can raise the likelihood of bowel cancer and may lead to genetic counselling or earlier surveillance for families.

A tumour can grow through layers of the bowel wall and may spread to nearby lymph nodes or to other organs. Staging brings together scan, tissue and surgical information so that care can be planned. When cancer involves the liver, the team may discuss this as liver metastases and review options with specialists from several disciplines.

Ageing, a personal history of bowel polyps or inflammatory bowel disease, some inherited conditions, smoking, regular alcohol intake, low activity and a diet high in processed meat can contribute to risk. Risk is individual: these factors do not predict what will happen to one person. Tell your clinician about relatives with bowel, uterine or related cancers.

A clinician will ask about symptoms and family history, examine the abdomen and may perform a rectal examination. Colonoscopy lets the doctor inspect the bowel and take a small tissue sample. If cancer is confirmed, scans describe its extent. Genomic tumour profiling may examine features in the cancer cells that can inform later treatment choices.

Surgery to remove the affected segment of bowel is a main treatment for many people. The surgeon may reconnect the bowel or, in some situations, create a stoma. Radiotherapy is used more often for rectal cancer, particularly when shrinking or controlling disease around the rectum is helpful.

Drug treatment may be given before or after surgery, or for cancer that has spread. The regimen and sequence depend on the stage, tumour features, fitness and personal priorities. Your team should explain the goal of each treatment, expected side effects and how these will be monitored.

Bowel function, appetite, energy and body image can change during treatment. A dietitian, stoma nurse, physiotherapist and psychological support professional can help with practical adjustments. Follow-up appointments may include symptom review, blood tests, scans or bowel examinations according to your treatment plan.

Not every case can be prevented. Avoiding tobacco, limiting alcohol, staying active and choosing fibre-rich foods can support bowel health. Screening and colonoscopy can find polyps or early changes before they cause symptoms; eligibility and timing depend on personal and family history.