Clinical features

Once a cancer has developed in the bowel wall it will continue to grow larger until it has caused enough symptoms to be investigated. The location of the cancer determines the symptoms. Sometimes there may be no symptoms at all until the tumour is very large.

Symptoms from the primary tumour in the bowel may include-:

• Bleeding, this may cause anaemia (a low blood count) which can lead to tiredness and breathlessness. The bleeding may not be obvious if it is well mixed in with the motion e.g. often bleeding from caecal cancer is not noticed and the first symptom is anaemia.
• Change of bowel habit - diarrhoea, constipation or alternating diarrhoea and constipation. These symptoms are more likely when the tumour is closer to the anus. A tumour in the rectum can cause a sensation of needing to go to the toilet but there is nothing to pass, otherwise known as ‘tenesmuses.
• Bowel obstruction – resulting in emergency admission to hospital for treatment – tumours anywhere along the bowel can cause this.

A mass may be palpable on examination of the abdomen, particularly in thin patients; this is likely to be mentioned in the supporting documentation but not by the patient. It is not a sign of severe disease and is a more common finding in thin patients.

Symptoms of advanced disease may include any of the following-:

• Jaundice
• Severe weight loss
• Abdominal swelling
• Shortness of breath
• Extreme fatigue and dizziness

Bowel obstruction

When colorectal cancer completely blocks the bowel this is an emergency. The person will become seriously ill, perhaps vomiting and become rapidly dehydrated. Emergency surgery will usually be performed within a couple of days of admission to remove the tumour and unblock the bowel. Emergency surgery is more risky and patients take longer to recover from this than planned (elective) surgery. This extra recovery time may delay the start of any postoperative adjuvant treatment such as chemotherapy. When assessing the duration of the award it is worth remembering that patients presenting in this way may take much longer to completely recover than someone with exactly the same disease who did not develop bowel obstruction. Minimal investigations will be done in these cases prior to the operation and staging investigations may be performed after the emergency operation.

Rectal cancer

These tumours are located very close to the anus, bleeding and change in bowel habit will be early and obvious signs of disease, enabling the patient to seek help at an earlier stage than with a similarly sized cancer higher up in the bowel.

Amended February 2009