Bowel Cancer

More than 90% of patients with early bowel cancer (stage 1), who are treated by surgery, are alive at 5 years

Colorectal cancer is the second most common cancer in men and women in Australia, excluding skin cancers. 1 in 12 Australians will be diagnosed with bowel cancer by the age of 85.

How do we diagnose bowel cancer?

The majority of people with bowel cancers do not have any genetic or familial cause for bowel cancer. The most common presentations are

  • Unexplained weight loss
  • A change in your bowel habit
  • Blood in the stool or unexplained anaemia
  • Abdominal pain

The diagnosis of bowel cancer can only be done via colonoscopy. Blood tests and CT scans can be useful tools, but directly visualising the inside of the bowel and taking a small sample (biopsy) is the only way to accurately diagnose cancer.

What now after the diagnosis?

If the colonoscopy has proven a bowel cancer is present, then you must have your cancer staged. Staging is the process of assessing the size and location of the tumour as well as determining if the cancer has spread.

For colon cancer (cancer of the large bowel) staging consists of

  • Blood tests
  • CT scan of the chest and abdomen

For rectal cancers, staging also consists of closely looking at the rectum and the depth of invasion of the cancer, by either

  • MRI scan, or
  • Endorectal ultrasound

How does staging affect what I do?

Staging determines the depth of invasion of the cancer.

Stage 1 – superficial invasion limited to the mucosa (lining) of the bowel

Stage 2 – spread to outer lining of the bowel

Stage 3 – spread beyond the bowel to the local tissue or lymph nodes

Stage 4 – Spread to other organs (metastasised), commonly to the lungs or the liver

Stage 1 and 2 is treated with surgery alone, whereas stage 3 disease is usually treated with surgery followed by chemotherapy. Stage 4 disease may require chemotherapy or radiotherapy before surgery.

Rectal cancer differs somewhat, in that stage 3 cancers are treated with chemotherapy and radiotherapy before surgery in order to reduce the chance of local recurrence.

How did I get bowel cancer?

Only a minority (15%) of bowel cancers are due to a hereditary component. The majority arise from both known and unknown environmental and lifestyle factors. The most important risk factors for bowel cancer are

  • Advancing age
  • Inherited genetic risk
  • Inflammatory bowel disease (Crohn’s disease and Ulcerative colitis)
  • Alcohol consumption
  • Smoking
  • Obesity

Generally bowel cancer involves a stepwise process in which a series of mutations occur in cells over a period of time. This initially results in benign polyp, but these polyps can undergo further mutation and become a cancer which has the capability of invading the bowel as well as the potential to spread to other organs

The purpose of bowel cancer screening is to hopefully detect, and remove, asymptomatic bowel polyps and cancers. Bowel cancer may be present for many years before demonstrating any symptoms.

Prognosis

Prognosis is the predicted course or probable outcome of your disease.

Survival of bowel cancer depends not only on your general health and age, but also on the stage of your cancer.

With stage 1 colorectal cancer, 90% of patients will be alive at 5 years. This percentage decreases with higher stage disease, which is why it is so important to diagnose bowel cancer early.