University of Calgary study suggests ‘overdiagnosis epidemic’ in thyroid cancer

A study by researchers at the University of Calgary suggests there’s an overdiagnosis epidemic when it comes to thyroid cancer and that many people who are told they have the disease don’t actually require treatment.

“It looks like maybe 20 per cent of those who are currently being treated for it are the ones who really have it, so a large fraction really don’t,” said Dr. James Dickinson, one of the study’s co-authors.

Dawnelle Topstad and James Dickinson pored over four decades worth of Canadian data on the disease.

They found thyroid cancer incidence rates in Canada increased by almost six times in women and five times in men between 1970 and 2012.

There was a big spike after the early 1990s and the sharpest increase was in women between 40 and 60.

At the same time, the rates of people who died from the disease were low throughout the period, with little variation between men and women.

The researchers say there are likely to be consistently small numbers of lethal thyroid cancer cases, but many tumours detected don’t progress or progress too slowly to pose much of a risk.

“In thyroid cancer, the vast majority of these tumors are in fact low-risk,” said Dr. Kevin Higgins, a head and neck cancer specialist at Sunnybrook Health Science Centre. “The survivorship is excellent and in fact, if we ultrasound people off the street over 60 per cent of these individuals would have a nodule.”

Higgins believes it may actually be better to actively monitor patients with a thyroid cancer diagnosis, instead of rushing into treatment.

“We need to be selective, we need to be cognizant that there is a tendency in some instances to overdiagnose and to over-treat, and we should first do no harm.”

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The study was published in CMAJ Open.

With files from Global’s Heather Yourex-West