What is Bowel Cancer?
The bowel is part of the digestive system. It is divided in two:
- The small bowel
- The large bowel
The food we eat ends up in the large bowel. Here, water and some nutrients are absorbed, leaving waste. Waste passes through the rest of the large bowel before leaving the body.
Symptoms of bowel cancer
The symptoms of bowel cancer can include:
- Changes in bowel habits: Diarrhoea, constipation, or narrowing of the stool for no obvious reason for six weeks or more.
- Blood in the stool: Rectal bleeding, either bright red or dark and tar-like.
- Abdominal discomfort: Cramps, pain, or bloating that won’t go away.
- Physical changes: A lump in your back passage or tummy (abdomen).
- Unexplained weight loss: Sudden weight loss without trying.
- Fatigue: Feeling constantly tired and lacking energy, even with enough rest.
- Anaemia: Iron deficiency causing weakness and paleness due to chronic bleeding.
Note: These can also be symptoms of conditions other than cancer, but it’s important to see your doctor if you notice them.
The ‘stages’ of bowel cancer
The ‘stage’ of a cancer describes how big it is and whether or not it has spread. This is vital because treatment is often based on the stage of a cancer.
Diagnosing the stage
‘Clinical’ stage testing: The tests and scans you have during diagnosis provide the initial clinical stage.
‘Pathologic’ stage testing: During surgery, the doctor finds out more. Tissue and lymph nodes are examined in a lab. These results are combined with the clinical stage to give a more accurate “pathological” stage.
TNM Staging System
Doctors use the TNM system to categorize the cancer:
- T (Tumour): The size of the primary tumour.
- N (Node): If any lymph nodes contain cancer cells.
- M (Metastasis): If the cancer has spread to other parts of the body.
Tumour Size (T)
- T1: Tumour is only in the inner layer of the bowel.
- T2: Tumour has grown into the muscle layer.
- T3: Tumour has grown into the outer lining.
- T4: Tumour has grown through the outer lining into nearby organs.
Grading of bowel cancer
Grading describes what the cells look like under a microscope. This helps doctors predict how the cancer is likely to behave:
At a Glance: Cancer Grading
The grade tells doctors how “differentiated” the cancer cells are compared to healthy cells. This helps predict how quickly the cancer might grow.
| Grade | Cell Description | Likely Behavior |
|---|---|---|
| Grade 1 (Low Grade) | Well differentiated: Cells look very similar to normal, healthy bowel cells. | Usually slower growing and less likely to spread quickly. |
| Grade 2 (Moderate) | Moderately differentiated: Cells look more abnormal and less like healthy cells. | Falls between Grade 1 and 3 in terms of growth speed. |
| Grade 3 (High Grade) | Poorly differentiated: Cells look very abnormal and disorganized. | Likely to grow more quickly and has a higher chance of spreading. |
