Large bowel cancer (colorectal)

Large Bowel Cancer on a lower digestive system body diagram

Facts and figures about large bowel cancer

Bowel cancer is the 4th most common cancer in the UK, accounting for 13% of all new cases. Approximately 66% arise in the colon and 34% in the rectum.

Higher incidence in men, male to female ratio being approximately 13:10, with the greater variation being in those diagnosed with rectal cancer rather than colon cancer.

Age related, incidence rises sharply from the age of 50 years, 95% being diagnosed in those over 50 years and an average of 43% in the 75+years age group. 98% are adenocarcinomas.

Risk factors include a diet high in red and processed meat, being overweight or obese, high alcohol intake and smoking. Also, increased by some medical conditions; adenomas/polyps, inflammatory bowel disease (Crohn’s or ulcerative colitis), metabolic syndrome, familial adenomatous polyposis (FAP), hereditary non-polyposis colorectal cancer (HNPCC), BRCA1 gene mutation (particularly in younger women) and having a first degree relative diagnosed with colorectal, this increases the risk by 80% and is higher again in those with more than one relative or relative diagnosed at a young age.

The NHS National Bowel Screening Programme introduced in 2006 offers screening every two years to anyone aged between 60 and 69 years of age (older patients can request screening) and studies have shown that bowel cancer deaths in those screened have already decreased by about 25% and it has the potential to reduce these deaths by 60%.

Screening involves a faecal occult blood test of the stools and if the result is abnormal then referral for a colonoscopy.

Large bowel cancer symptoms

  • There may be no symptoms for those detected at screening as diagnosis from this may occur 2-3 years prior to those presenting with symptoms.
  • Change in bowel habit.
  • Constipation/diahorrea.
  • Blood or mucus in the stools.
  • Straining with an empty bowel (tenesmus).
  • Pain on defeacation.
  • Loss of appetite or weight loss.
  • Nausea and vomiting.
  • Abdominal/pelvic pain.

Diagnosis of large bowel cancer

Investigations may include:

  • FOBT and further colonoscopy/sigmoidoscopy following screening.
  • Physical examination (including rectal examination).
  • Blood tests (including FOBT if not participant in screening programme).
  • Flexible sigmoidoscopy and possibly proctoscopy.
  • Colonoscopy.
  • Barium enema.
  • Chest X-ray.
  • Ultra sound scan.
  • CT scan.
  • PET scan.
  • MRI scan.

Large bowel cancer treatment

Depends on several factors:

  • The position of the tumour.
  • The type and size of the tumour.
  • The grade of the cancer cells.
  • The stage of the cancer.
  • General health.


Surgery is the main treatment for bowel cancer; approximately 80% of patients will have surgery. The type of operation i.e the section removed depends on where the tumour is in the large bowel.

In early stage disease, it may be possible to remove the tumour and some of the surrounding healthy tissue. Lymph nodes near the tumour site will often be removed during the surgery.

In most cases the two sections of bowel either side of the resection can be joined together to enable normal bowel function to be maintained but occasionally this may not be possible and a section of the bowel is brought to the surface of the abdomen to form a stoma (colostomy), sometimes this is temporary to allow the bowel to heal and a stoma reversal operation can be performed later. However, this is not always possible so the colostomy may be permanent, particularly in tumours low in the rectum. In advanced cases, surgery may be required to remove a bowel obstruction.


Radiotherapy is not often used for colon cancer due to the sensitivity of the bowels to radiation. However it may used pre-operatively (neoadjuvant) in early stage in rectal cancer, often combined with chemotherapy to try and reduce the tumour, allowing a surgical resection and possibly reducing the necessity for a colostomy and reduce the risk of recurrence.

Radiotherapy/chemoradiation may be prescribed post-operatively (adjuvant) if the tumour was difficult to remove, if there is thought to be a risk of recurrence or if the lymph nodes were found to contain malignant cells. Palliative radiotherapy may be advised in advanced cases where the disease has spread outside of the bowel to try and shrink the tumour and slow the disease progression to relieve symptoms such as pain in the pelvis or rectum.


Chemotherapy is sometimes used in combination with radiotherapy (chemoradiation. The chemotherapy makes the cancer cells more sensitive to the radiation, so this combined treatment is likely to be more successful than radiotherapy on its own. It may be given before or after surgery either to reduce the size of the tumour and reduce the risk of recurrence or if it is indicated at surgery as described above.

The chemotherapy drugs usually used are fluorouacil (5FU) or capecitabine.

Biological therapy

Cetuximab is a monoclonal antibody that is being used in some advanced bowel cases. Cetuximab blocks epidermal growth factor (EGF) which is a protein that attaches to receptors on cancer cells and encourages them to grow.

Cetuximab with chemotherapy has been shown to extend the survival of some patients with advanced bowel cancer and improve their quality of life. It is usually given with the chemotherapy drugs 5FU (fluorouracil), oxaliplatin, or irinotecan.

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