Bowel cancer may be diagnosed after you visit your doctor with symptoms, or if a screening test shows signs that you might have bowel cancer.

You might have a number of tests to investigate your symptoms and confirm a diagnosis of bowel cancer, including:

• physical examination
• blood test to check for anaemia
• internal examination of the rectum, anus and colon – this may include a sigmoidoscopy or colonoscopy
• imaging of the bowel, which may include a barium enema, computed tomography (CT) scan or magnetic resonance imaging (MRI)
• biopsy from the bowel wall for examination under a microscope.

Stages of bowel cancer

If you are diagnosed with bowel cancer, you might have more tests to determine the stage of the disease and whether the cancer has spread to other parts of the body. Knowing the stage of the disease helps your medical team plan the best treatment for you.

Bowel cancer is divided into four stages, depending on whether the cancer has spread through the bowel wall to other organs or lymph nodes:

• Stage 0 (carcinoma in situ): there are abnormal cells in the bowel lining that may become cancerous
• Stage I: the cancer has spread from the bowel lining to deeper layers of the bowel wall (submucosa or muscle)
• Stage II: the cancer has spread through the muscle of the bowel wall and may have spread to nearby organs
• Stage III: the cancer has spread to nearby lymph nodes and organs
• Stage IV: the cancer has spread through the lymph nodes or blood to other parts of the body such as the lungs or liver.

Tests to determine the stage of bowel cancer can include:

• CT, MRI or PET (positron emission tomography) scans
• chest X-ray (to see if the cancer has spread to the lungs)
• lymph node biopsy
• ultrasound.