Never had a colonoscopy? Should you?

A new set of guidelines recommends having one if our risk of bowel cancer is more than 3% over the next 15 years. And there’s an online calculator to help us work that out.

If we have a family history of bowel disease or we’ve had gut issues or internal bleeding, our GP will probably have recommended it.

In my own case, I had a colonoscopy about seven years ago for no reason other than that I was in my mid-50s, I wondered if it might be time to check and my GP agreed it was a reasonable idea. Since it was clear, I didn’t respond to the letter five years later to say that I was due for another one.

My mother, on the other hand, was in her 80s and had never had one. It wasn’t until she had chronic iron deficiency despite taking iron supplements that her doctor suggested it. It showed she had bowel cancer.

So for people without symptoms, there hasn’t been a clear guideline as to whether we should or shouldn’t.

Which isn’t ideal given that bowel cancer is the second most common cancer for women, after breast cancer, and each year more than 7000 of us are diagnosed with it. The average age of diagnosis for women is 72 (compared to 68 in men).

We now have a national bowel cancer screening program that’s free for people aged 50 to 74. It’s been heavily advertised so you’d be aware that every two years we’re sent a kit that involves collecting a stool sample that goes to a lab. The analysis can detect blood that’s not visible to the naked eye.

About 1 in 14 samples yield a positive result (when it comes to medical tests, a negative result means there’s nothing there and a positive one means there is).

In Australia about 41% of eligible people participate — around 43% of women and 39% of men). The group with the highest participation is those aged 70-74.

In recognition that there’s not much uniformity amongst bowel cancer screening arrangements around the world, an international team led by Norwegian researchers recently investigated whether it makes a real difference to health outcomes for people starting it when they’re aged 50 to 79.

In the process they came up with guidelines based on the use of a tool developed in the UK called QCancer. This is the online calculator I mentioned.

If we have less than a 3% risk over the next 15 years screening isn’t recommended. Procedures such as colonoscopies do involve a chance of harm, e.g. bowel perforation.

When I include my mum’s bowel cancer it pushes me over 3%. The main risk factor for bowel cancer is age, so if nothing else changes I’d probably look to do another one when I’m closer to 70.

Bear in mind that these guidelines are for people who’ve never been screened.

Finally, given there’s not much we can do about the age factor, the other ways to avoid bowel cancer are to not smoke, be moderate with alcohol, eat a healthy fibre-rich diet, get regular exercise, and avoid obesity. Diabetics also have a higher risk.

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