I received a letter from the British Columbia Colon Screening Program (BCCSP) recently. Like the NHS in the UK, this program recommends faecal immunochemical tests (Fit) – stool samples that check for microscopic traces of blood – every two years to screen 50-75-year-olds for bowel cancer. They were trying unsuccessfully to get feedback from one of my patients who was referred for a colonoscopy after a positive Fit – could I give them information instead? I knew why they hadn’t heard anything. I entered David’s records to get the details for my answer.
It was the registration in October last year when David had joined my list, aged 72, after his former GP had retired. We had talked about his previous heart valve replacement, atrial fibrillation and mild heart failure, reviewed his (negligible) symptoms and medication. Then I turned the conversation to preventive matters. No, he told me, he hadn’t had a Fit for at least ten years. I offered to organize one. He would be eligible for a few more before crossing the age limit.
Then there was the positive result, the colonoscopy referral, and the news of the unmistakable cancer growth in David’s colon. I looked at the follow-up clinic notes planning the surgery to remove the growth and the factors that suggested there was no sign that it had spread.
I remember thinking at the time, like David, how lucky he had been. Thanks to a simple test, a cancer had been detected at a stage where there were good prospects for recovery. The surgeon hoped to excise it using keyhole techniques, but warned that conversion to a wider open procedure might be required. David told me he was prepared for both and was keen to remove the tumor.
That was the last time we spoke. Open surgery had proved necessary, but it had gone well. Then the ileus had set in – a known complication where the bowel is temporarily paralyzed in response to operative trauma. This had led to aspiration of vomit into the lungs and a cardiac arrest. They managed to get David back and into the ICU, only for his heart to stop again, this time irreversibly.
It was helpful to read those recordings again, just in the quiet of my consulting room. How that innocuous conversation last October was the start of a chain of events that would, within months, end David’s life. What if I hadn’t mentioned Fit? What if he told me he hadn’t bothered with them for the last ten years and wasn’t going to start doing so now? How much of his agreement to perform one was because he didn’t want to offend this young doctor from England, whom he was grateful to accept?
Doctors are well aware that any drug, surgery, test, or other intervention carries a risk of harm as well as risk of good—something that is grossly underestimated in popular discourse. Was the information I had given David balanced enough for his decision to review? These days, I advise standard-risk female patients that mammography screening, while marginally reducing breast cancer deaths, does not save lives. The more patients die from complications of treatment – magnified by the fact that screening detects many tumors that would never cause disease – the better their prognosis. Researching the latest literature, I discovered what I didn’t know last October and is still not being discussed: the same goes for Fit. The evidence supporting these screening programs is biased towards identifying positives but weak in capturing data about harm.
How long would it have taken for David’s cancer to manifest itself if he hadn’t taken that Fit? Would he ever have done that? The perception of the show as an unalloyed good is thwarted not only by the bias of scientific data, but also by the stories we can hear. Those who survive the diagnosis and treatment of cancer understandably proclaim what feels like their greatest asset. But the dissenting voices, of people like David who never lived to tell their story, have long been silenced.
(Further reading: Degradation of Independence)
