It’s always strange emerging from the single-mindedness of a conference to breathe the outside world’s unconcerned air. I doubt there was a person attending the British Medical Journal’s recent “Preventing Overdiagnosis” conference in Oxford who didn’t come away with the sense that overdiagnosis and its consequences is one of the biggest challenges facing health providers globally.
But beyond the concern of a handful of international experts – many of whom were gathered in Oxford – awareness and concern among the international cancer community seems low. Yes, most of us know that there are risks as well as benefits to breast cancer screening, and that PSA testing for prostate cancer can lead to unnecessary tests and treatment. But does that result in changes to practice? Does every one of us need to sit up and listen a bit more?
The papers presented at the conference certainly suggested “yes”. As keynote speaker Ilona Heath, a former President of the Royal College of General Practitioners, said: “Susan Sontag’s kingdom of the well is being absorbed into the kingdom of the sick, and clinicians and health services are busy ushering people across this important border in ever-increasing numbers. The costs, personal, social and economic, are enormous.”
The issue of overdiagnosis doesn’t just hover over breast cancer and prostate cancer.
The conference heard evidence that it is an issue in melanoma. An analysis of data by America’s National Cancer Institute, presented at the conference, showed that melanoma incidence has been increasing since 1975 while mortality has remained stable, strongly suggesting overdiagnosis.
Or take ovarian cancer. The conference heard about concerns that improved testing with blood tests and ultrasound are leading to increased detection of borderline ovarian tumours that might never present clinically in the lifetime of a woman.
Or thyroid cancer. A population-based study of thyroid cancer patients in Ontario, Canada between 2000 and 2008 shows that this relatively benign cancer is increasing at an “epidemic” rate. The increase seems to be confined to more affluent areas, and closely related to the availability of diagnostic ultrasound.
The suggestion is that, without sophisticated diagnostic techniques, large numbers of people with these diseases would have died of something else without even knowing they had cancer. They might have avoided distressing decisions, painful tests, potentially disabling treatments.
Such interpretations of data can prove controversial. Some evidence is strong, some is preliminary to say the least. But it undoubtedly opens up important questions for all those involved in the detection and treatment of cancers. It asks us to look up from a heads-down determination to track down and destroy cancer, and question whether sometimes – quite often – doing nothing is the best course.
It’s not an easy thing to do. Cancer World will be exploring the issues in its next three editions.