When it comes to thyroid cancers, the more you look, the more you find. Scanning technology developed over the past few decades has made it easier to find small thyroid nodules, even when scanning other parts of the body (these are called “incidental findings”). More scanning has led to an increasing number of thyroid cancer diagnoses, even as thyroid cancer mortality rates have remained stable.
A recent study in JAMA Internal Medicine provides a prime example of how more imaging can lead to increased incidental diagnosis of thyroid cancer. After the September 11, 2001 attacks on the World Trade Center, 15,000 firefighters and EMTs that responded were given chest CT scans in the following years, to detect potential lung disease from inhalation of dust and fumes. Looking at 17 years of data, researchers found that these first responders were more than twice as likely as non-first responders to have a thyroid cancer diagnosed, even though first responders were not screened specifically for thyroid cancer.
The rate at which first responders with symptoms of thyroid cancer were diagnosed was the same as non-first responders; however, rates of asymptomatic thyroid cancer were three times higher in first responders. This indicates that the excess thyroid cancers found incidentally in these rescue workers were overdiagnosis.
Take the thyroid out…of images
Overdiagnosis of thyroid cancer often leads to additional biospies, scans, and removal of the thyroid, which can cause significant physical and financial harm. Reducing overdiagnosis caused by incidental findings would go a long way to preventing unnecessary harm to patients–but how do we accomplish this? In an accompanying editorial, Dr. H. Gilbert Welch from the Brigham and Women’s Hospital argues for a simple way to reduce overdiagnosis of thyroid cancer through incidental findings: Stop including images of the thyroid in scans of other body parts.
Welch acknowledges that hiding a part of a scan result seems like a radical idea. But it may be the best thing for both doctors and patients. If we were to “mask” the thyroid out of CT and MRI results (unless specifically ordered by a doctor), doctors and patients would not feel pressured to undergo thyroid removal or further unnecessary imaging. This would also save radiologists the time of having to “search through an avalanche of cross-sectional images…uncertain whether doing so genuinely reflects the patient’s best interest,” writes Welch.
Screening for thyroid cancer for asymptomatic people is not recommended, and guidelines now recommend not taking a biopsy for small cancers found incidentally. Removing the incidental findings themselves should be the next step in reducing overdiagnosis of thyroid cancer.