Symptoms of colon cancer

Possible bowel changes include diarrhoea, constipation, altered stool shape or a persistent feeling of incomplete emptying. Some cancers cause few noticeable symptoms at first. None of these experiences can confirm cancer without clinical evaluation.

The presentation can vary with the tumour's location and how it affects bleeding or passage through the bowel. Slow blood loss may lead to anaemia, which can cause tiredness, breathlessness, paleness or reduced exercise tolerance.

Pain, bloating, reduced appetite and weight change may develop, while narrowing of the bowel can cause cramps, vomiting or difficulty passing stool and gas. Benign bowel conditions can cause similar symptoms, making investigation more useful than self-diagnosis.

Arrange an appointment for a new, unexplained or persistent bowel change, visible blood, recurrent abdominal discomfort, unusual fatigue or unintentional weight loss. Mention family history, previous polyps and all medicines, including blood thinners and iron.

The clinician may examine the abdomen and rectum and request blood or stool tests. Colonoscopy may be used to view the bowel lining and take tissue from an abnormal area. The choice and timing of tests reflect the complete symptom pattern and examination.

Get urgent medical help for heavy bleeding, black tar-like stool with dizziness, fainting, severe or rapidly worsening abdominal pain, repeated vomiting, pronounced swelling, or inability to pass stool or gas.

Marked weakness, breathlessness at rest, confusion or collapse also require immediate assessment. These warning signs may reflect bleeding, anaemia, dehydration or bowel obstruction and should not wait for a routine visit.

Ask which features of your symptom pattern guide testing, whether anaemia is present, whether colonoscopy is suitable and what preparation it requires.

Confirm when results will arrive, who will explain them, what happens if symptoms continue despite a reassuring test and which changes warrant urgent reassessment.