Bowel cancer screening: a case of simple medicine saving lives

Dr Simon Cowap discusses a welcomed package he recently received in the mail, and discusses the significance of this important initiative for all Australians.

  Most of what turns up in the old fashioned snail mail box these days is unsolicited junk, so I don’t bother checking it on a daily basis any more. It’s the same with the landline at home – it hardly ever rings and when it does it’s almost always someone asking for money. But just as I have to answer the phone on the off chance it’s an aged techno-phobic relative, not everything in the mailbox is a hardware flyer or bill I’d rather ignore (though actually I do quite enjoy hardware flyers – surely all that’s standing between me and the home beautiful is all those fabulous looking tools?).  

The last time I checked, nestling among the restaurant menus and ads for local plumbers was a bulky envelope from the Australian Government. Uh oh. Was it the tax office? Was Medicare auditing me? Had I somehow let my citizenship slip and was about to be deported to Nauru? In reality I lead a dull and blameless life, but somehow the sight of police officers and official stationery always makes me feel guilty.  

In fact, this was the government doing me good, for it was none other than my faecal occult blood testing kit. And while the thought of collecting a stool sample doesn’t make most of us jump for joy, it probably should because the National Bowel Cancer Screening Program (NBSCP) is actually a great initiative that doesn’t always get the credit it deserves.  

It seems to me that we spend a lot more time talking about breast, cervical and prostate cancer screening than we do about bowel. Bowel cancer incidence (estimated to be 16682 in 2017) is almost as common as breast cancer (17730) and almost identical to prostate cancer (16665). And when it comes to mortality, bowel cancer is second only to lung cancer, killing more Australians (an estimated 4114 in 2017) than both prostate and breast. Cervical cancer, thanks in no small part to screening and HPV vaccination, is estimate to cause a relatively lowly 254 deaths this year.  

I just hope all the time and energy we spend debating the pros and cons of PSA screening doesn’t detract from encouraging our patients to engage in the far more worthwhile practice of bowel cancer screening. Unlike all the uncertainty that pervades PSA screening, the guidelines for if/how/when we should screen for bowel cancer are crystal clear as set out in places like the RACGP Guidelines for preventative activities in general practice. For most of us, it’s FOBT once over 50, for others a colonoscopy.  

The benefits are also clear. A recent paper in Lancet Public Health evaluated the long term benefits, harms and cost-effectiveness of the Australian NBSCP. They estimated that at the current participation rate of 40%, it is expected to prevent 92 200 cases of bowel cancer and 59 000 deaths over the period 2015-2040. To achieve this we would need to be performing 101 000 programme related colonoscopies in 2020, associated with 270 adverse events. If we could increase the participation rates to 60%, an additional 37 300 cases and 24 800 deaths could be prevented over the same time. It was estimated that 1.7 billion dollars in health costs would be saved over the decade 2030–40 as a result of screening at the 40% participation rate, climbing to 2.1 billion of 60% participated.

I just hope all the time and energy we spend debating the pros and cons of PSA screening doesn’t detract from encouraging our patients to engage in the far more worthwhile practice of bowel cancer screening.

  Of course we’re not saving a life every time we get a patient to have an FOBT. The overall number needed to screen (NNS) is 647-788 per death prevented. So if there are about 1500 patients in an average GP’s practice, and 1/3 of your patients are over 50, even if you screened all of them you’d save less than one life a year. As a comparison, the NNS for mammography to prevent breast cancer deaths ranges enormously in different studies, from 84 – 2000. Controversy still rages regarding how many, if any, lives are saved and at what cost by screening asymptomatic low risk men for prostate cancer. (A recent mathematical reanalysis of data from the landmark PLCO trial by Etzioni et al in the Annals of Internal Medicine suggested that contrary to the original authors’ findings that there was no mortality benefit from PSA screening, the data in fact showed a mortality benefit of 30%. As expected, this claim the initial authors got the maths wrong has itself attracted controversy…)   

Medicine is often far too complicated, as exemplified by PSA screening. All too frequently the closer you look at something the murkier it gets. And yet patients expect clear recommendations from their doctors, preferably along the lines of do this simple thing and it will both help you not die from cancer and be highly unlikely to hurt you. The NBSCP is far from perfect; you do still have to explain about false positives and false negatives, and there is a certain ‘yuk factor’, but in the real world it’s about as close to simple as medicine gets in 2017. So let’s celebrate it and see what we can do to save those extra 24 800 lives. 


Simon CowapDr Simon Cowap MBBS (Hons), FRACGP
Simon is something of an accidental GP who likes to pretend he’s an artist trapped in a professional’s body. He dropped out of his first degree (arts) and went to London to play bass guitar in a band too musically challenged even for punks. Dropping back in to university, he subsequently also failed to complete a science degree and a Masters of philosophy. His remarkable lack of artistic success has been continued by the non-publication of his several novels. Somewhere along the line he did finish a medical degree. He still harbours dreams of literary success but his family have forbidden him to give up the day job.