Demystifying Bowel cancer
Are you at risk?
There are a lot of colourful sayings in medicine. The most graphic tend to be those from the surgical fraternity, perhaps unsurprisingly. One of my favourites is “never let the sun go down on undrained pus”, an aphorism that is just as appropriate for dentists. Another (less appropriate for you, I trust) is about haemorrhoids. When approaching the surgical removal of these, one should bear in mind that “If it looks like a clover, you’re troubles are over, if it looks like a dahlia, you’re bound for failure” . I trust no explanation is required. I just wish that we had a saying for bowel cancer that resonated. The essence is that if a patient has blood associated with defecation, it demands investigation. (If you email me with suggestions, I will include them in next month’s edition, and arrange a prize!)
The fact is, bowel cancer is the most common cancer in the Western world, including Australia. Twelve and a half thousand cases are diagnosed each year and there are 4,500 deaths. In NSW, you have a 1 in 22 chance of getting bowel cancer by the time you are 75, 1 in18 if you are a man, 1 in 28 if you are a woman. And yet it is the most curable cancer if caught early.
Ah, early detection. We’ve had programmes for years now to detect early cervical cancer in woman (with great success) and there is now a breast screening programme for older women. The race is on to develop an early detection tool that is similarly accurate for cancer of the prostate, but (as discussed in earlier articles) the PSA blood test and Digital Rectal Examination (DRI, or the “finger test”) are the best we have as yet. Then why has bowel cancer taken so long?
Well, partly because it is because the bowel lacks glamour. Most people don’t discuss their bowel habits with mere acquaintances, and are reluctant to mention it to their doctor, unless probed. Also, if you notice a bit of blood in the toilet bowl, it is easy to attribute it to a haemorrhoid, or the beetroot you ate the other night. The symptoms of bowel cancer are also quite vague, until you get to the stage where you have frank abdominal pain, start to lose weight or develop jaundice. So, many people ignore the subtle symptoms, but when they look back they had been aware that all was 'not quite right'. They just put it off.
If you are over 45, and your bowel habit changes from your usual pattern to constipation or diarrhoea, and that change lasts more than two weeks, you need to at least run it by your doctor. Likewise, if you notice blood (red or dark) passed with a bowel motion, or anything else that is not normal for you, check it out. You may be embarrassed, but we won’t. The last time I was embarrassed was (XX years ago) in a labour ward, when I asked the grey-haired man present whether this was his first grandchild? (you can guess the rest). A sixteen-year-old boy did try to embarrass me recently. I was participating in a “GPs in Schools” programme, where kids in small groups get to spend two hours with a doctor discussing anything they choose. “Is it normal to masturbate fifteen times a day?” he asked. “Normal!” I cried, “That’s a bare minimum!”
On that note, there is also no reason to be frightened of what the doctor may ask you to do, or do to you. The worst thing that can happen is you’ll be referred for a colonoscopy, and even that is not not so bad. Colonoscopies are a bit like vasectomies, in that people take a long time to work up to having them, but when it's all over, they delight in bragging about how easy it all was.
But let’s backtrack. Bowel cancer starts as tiny outgrowths on the inner bowel wall, called polyps. These are pea shaped, and some have little necks, or ‘peduncles’ and some do not. Many are harmless, but about 20-30% have the potential to develop into cancer over 5-25 years. You usually can't tell whether you have any polyps, but polyps do tend to bleed. However, by the time the blood has travelled to the outside world, it has denatured and turned black or very dark brown, so you may not be able to see it, either in the bowl or on the paper. (That is, if you are looking. If you are over 40 and not checking out your bowel motions every time, this is the time to start). There is a test for this blood, which is called “faecal occult blood”. Doctors used to perform this by putting a finger in your anal canal, then wiping the residue on a slide and adding some drops of a reagent (yes, we have all the best jobs). If a colour change ensued, it meant that blood was present. This in turn meant that you had internal haemorrhoids, or maybe bleeding polyps, or, as an outside chance, bowel cancer.
In the past ten years, faecal occult blood testing (or FOBT) has become almost as sophisticated as pregnancy testing. There is now a little kit, where you smear a bit of your stool on a card in three places, then POST it off to a laboratory. Here, a (very) dedicated technical person adds the reagent, and notifies you of the result. There are several types available. The cheapest is the one that you can get from the Rotary Club or the pharmacy, which requires that you avoid meat for a few days before the test. Another one, called “InSure” is much simpler, but costs about $30. For this one there is no special diet, and it’s a bit more aesthetically appealing. (It was also developed in Australia, trialled worldwide and is now selling worldwide. You have probably not read about it in the Fin Review, as it is not an exciting subject). Large trials in the UK over the past five years have indicated that this is a cost effective way of screening populations for bowel cancer, so Australia is now adopting this. As 85% of bowel cancer occurs in people over 55, the programme that has been rolled out here is this: if you turn 55 or 65 between 1/5/06 and 30/6/08, you will be offered a FOBT for free. You may not have heard of it, because it is not the sort of thing that people discuss over drinks, but if you get sent one, just do it.
Now, unlike home pregnancy test, this test has more false positives than false negatives, which is great for the individual, as s/he is less likely to get missed if s/he does have bowel cancer. However, it is placing increasing demands on gastroenterologists, especially ones that are willing to Medicare those people with no health insurance who have a positive result, so waiting times are blowing out. Nevertheless, it is a very positive development. To catch bowel cancer at a stage when it can be easily stopped in its tracks with the snip of the biopsy forceps is very gratifying for patient and doctor, and very cost saving for the country. And usually this is the case, if polyps, even large ones, are picked up at colonoscopy. Colonoscopy involves you drinking 1-2 litres of a special ‘bowel prep’, as it is fondly known, which makes you go to the toilet like there is no tomorrow. But there is a tomorrow, and that is when you present to the clinic, are injected with very effective drugs (usually midazolam and fentanyl) which send you to sleep ('twilight sedation'). The specialist then inserts a flexible tube with very sophisticated fibre optics and checks out the inner surface of your colon almost all the way up to your stomach. S/he will usually take at least one picture which you may enjoy looking at later, depending on your personality. The best views are obtained in the most pristine colons, so don’t be shy about drinking enough ‘bowel prep’ to ensure that your insides run clean. If there are polyps or anything else unusual, it will be biopsied and/or removed on the spot.
These days you can also have a ‘virtual colonoscopy’, which is done as a very clever CT scan. Unfortunately you don’t get to drink ‘virtual’ bowel prep, so you still have to go through the day on the toilet, but the advantage is there is no need for anaesthetic as there are no tubes, so there is no down time. Virtual colonoscopies, or ‘colonography’, was quite controversial when it first arrived, which had a bit to do with turf wars between gastroenterologists and radiologists, but all the literature is now confirming that it is just as accurate.
Who should do a bowel cancer check?
Anyone can do a FOBT, and anyone over 45 should do one.
If you have a first degree relative or two 1st or 2nd degree relatives, diagnosed with bowel cancer before 55yrs: start having colonoscopies at age 50, or 10 years less than the relative's age at diagnosis.
If you have two or more 1st or 2nd degree relatives who have had bowel cancer, or multiple cancers or bowel cancer before 50 or endometrial/ovarian cancer: genetic studies are advisable, with bowel screening beginning in your 20s.
If bowel cancer is diagnosed early, five year survival in Australia exceeds 90%, so don't let it be pride or embarrasment that hold you back. And when you've done your check, tell your friends about it, so that, like the prostate, bowel cancer can become demystified.