King Charles III has been diagnosed with cancer. The diagnosis was, as far as we know a chance finding - it was announced following his recent treatment for an enlarged prostate. Chance cancer findings have a special name - incidentalomas! Incidentalomas are a common side effect of modern diagnostic medicine and screening. Many don’t need to be found and only cause anxiety for the patient and waste money and resources. On the other hand, it is possible, but unlikely, that finding it saves your life.
Chance findings of cancer are generally considered a good thing when they appear localised and have not spread. The importance of catching cancer early is relentlessly stressed in the media, but the evidence given to support these claims is often spurious and subject to important biases. The Independent provided such an example of this in relation to King’s cancer.
”spotting cancer early can increase survival rates and make treatments more effective.”
The problem with that statement, if you haven’t already spotted it, is that survival is the length of time from the point of diagnosis until death, if it occurs. It changes when you move the time of diagnosis and that itself might not make any difference to the outcome. The figure shows a hypothetical example of two people who are identical in all regards, except for Patient B had his cancer detected incidentally, at an early stage during a routine examination and Patient A did not.
Patient B appears to have survived longer simply because the diagnosis time was advanced - creating a lead-time. This will always happen when you diagnose early, irrespective of whether you change the outcome. This effect is called lead-time bias and it means that survival time is an unreliable measure when it comes to measuring of the benefits of earlier intervention.
If the King’s cancer was “incidental” then he is in good company A recent paper reported that 28.5% of all patients and 19.8% of high grade (HG) bladder cancer patients were diagnosed incidentally between January 2013 and February 2021. Interestingly, one of the ways incidental bladder cancers arise is following investigation for prostate problems. This could all be rueful speculation of course, but as far as we know his prognosis is good. A " schedule of regular treatments" sounds like chemotherapy or radiation, and not surgery and that would fit with the incidental finding. Whether any of this would have come to light without getting that prostate problem checked in the first place, we’ll never know and therein lies the problem.
Vivat Rex!