Colon cancer is more common than you might think, but it doesn’t have to be fatal. The key is early detection.

When Ben Korf (74) suddenly began struggling with diarrhoea in November 2008 he was not particularly worried. He went to his doctor for a prescription, and then headed off on holiday. But the diarrhoea persisted and on his return from holiday Ben went back to his GP.

In a way, he was lucky: his doctor suspected something was wrong and sent him for further tests. Five days later colon cancer had been diagnosed and 20cm of his colon had been removed.

The disease caught Ben completely off guard because his lifestyle was healthy. Other than breast cancer there was no history of cancer in his family. “I’d never smoked, I walked 6km every second day and I wasn’t overweight. I also went to an internist every year for a thorough check-up.”

Twenty-eight radiation treatments and six courses of chemotherapy later, his cancer is now in remission. Ben is optimistic about the future. “I have to go for an annual colonoscopy and six-monthly blood tests,” he says, “but I was lucky because the operation was over before I’d properly realised I had cancer.”

Common kind of cancer

Colon cancer is also known as colorectal cancer because it can affect the rectum too. It grows slowly and has no symptoms in its early stages, which is when the success rate of treatment is high, says Dr Paul Paradza, a clinical oncologist from Gauteng, South Africa.

That’s why regular testing is essential.

In Australia in 2012, 15,840 people were diagnosed with colon cancer, making it the second most commonly diagnosed cancer in this country. The good news is that it can be completely cured if it’s caught early enough. Plus, it’s also “extremely preventable”, Dr Paradza says.

And there’s more good news: colon cancer is one of the areas of research showing the best progress.

It usually affects those in middle and high income groups. Westernisation and urbanisation play a large role, Dr Paradza says. “It’s all about what we eat. A fat-rich diet with little fibre is often the cause.”

Studies also show a link between high cholesterol and colon cancer. “Being overweight and having too much body fat is dangerous for various reasons. Many toxins hide in fat and this affects not only your metabolism but also your immune system. It impairs your body’s chances of fighting cancer.”

People with ulcerative colitis or a history of Crohn’s disease also run a greater risk of developing colon cancer. In rare cases colon cancer is hereditary. The risk of getting it increases exponentially after the age of 50. But sometimes there is no obvious cause, which is why experts emphasise the importance of thorough testing when you experience unusual symptoms.

Danger signs

Be aware of the following danger signs:

    • Changes in your bowel movements. If you’re always constipated and suddenly start having diarrhoea or vice versa, mention this to your doctor. Likewise if you sometimes have constipation or very loose stools. Regular slimy stools are also a warning signal.

    • Blood in the stool is bad news. If your stool is dark red or black, or if you see blood in the toilet or on the toilet paper, have a thorough check-up immediately. Your doctor will first want to rule out haemorrhoids. Insist on a colonoscopy. If your stool is almost black it’s a sign of serious internal bleeding – although this symptom could indicate colon cancer it might also be an ulcer.

    • Severe, inexplicable tiredness as well as unusual weight loss.

    • Chronic and severe stomach cramps or stomach pain that doesn’t respond to ordinary treatment.

    • Bloating and a feeling of constantly being full.

    • Anaemia, especially in men over 40, can indicate bleeding in the colon that can’t yet be seen with the naked eye. Men over 40 who feel tired and don’t know why should have their iron levels tested. Your doctor will also have a stool sample tested for signs of bleeding.

How do doctors test for colon cancer?

There are a number of tests that can identify colon cancer. During a routine check-up your doctor will press on your stomach to feel for enlarged glands or an enlarged mass in the abdomen. A rectal exam might be done and faeces can be sent to be tested for bleeding.

Other tests include a barium enema (a contrast fluid is used before the patient is X-rayed), a sigmoidoscopy, colonoscopy and/or biopsy of suspect tissue. A sigmoidoscopy involves a slender tube that has a light being placed into the lower part of the colon through the rectum so a physician can look for cancer or polyps.

About 65% of colon cancers can be diagnosed this way. It’s particularly useful in detecting cancer in the lower part of the colon, which is easily missed with a colonoscopy. A colonoscopy is a similar procedure during which the entire colon is probed.

Both procedures are performed by a gastroenterologist. They’re not painful but they are uncomfortable and performed under a light anaesthetic. You’ll have to take medication before the procedure to clear out your intestines completely.

Tests to reduce the risk of colon cancer

Regular tests, whether you have symptoms or not, can dramatically reduce your risk of getting colon cancer. The biggest cause is adenoma polyps in the intestinal wall. Most are benign but there is a 1% chance that polyps can become malignant and the cancer can then spread in the colon and elsewhere.

Your doctor will remove polyps found during a routine examination and have them analysed. If they’re benign, the possibility of later malignancy is eliminated; if they’re malignant hopefully their removal will have been in time to prevent the cancer from spreading to the rest of the colon, which puts the chance of recovery at 90%.

Everyone should have themselves regularly tested for colon cancer from the age of 50. Possible tests include analysis of a stool sample, a sigmoidoscopy and a colonoscopy. Your doctor will recommend which tests you should have and, depending on the results, how often follow-up tests should be done.

If you’re in a high-risk group for colon cancer, you should start with a colonoscopy when you’re 40 and repeat it every year or two years. See your doctor about this.

According to the American Cancer Association, these factors put you in a high-risk group:

    • You have been diagnosed with polyps or another form of cancer.

    • You have Crohn’s disease or ulcerative colitis.

    • Polyps or colon cancer have been diagnosed in a parent, brother, sister or child under 60, or two such relatives over 60.

    • There is a family history of hereditary colon cancer, such as the type caused by polyps (also known as FAP) or the type not linked to polyps (known as HNPCC).


Surgery is almost always part of the treatment plan, and involves removing the affected area of the colon and neighbouring lymph nodes.

Usually the two healthy parts can be rejoined and your colon will function as it always did. Sometimes, however, it’s necessary to create an opening in the abdominal wall (called a colostomy) so excreta can be passed directly into a bag outside the body instead of through the rectum and anus. A total colectomy – when the entire colon is removed – can also be done.

After the operation the surgeon will refer you to an oncologist who will compile a customised treatment programme for you, which could include chemotherapy and radiation.

Each case of cancer is unique and treatment that works for one person may not necessarily work for your cancer. Your oncologist must take several factors into consideration such as the degree, type and situation of the cancer and whether it has spread to the lymph glands or nearby organs. Your general state of health and age will also be factored in.