The dramatic rise in thyroid cancer in America seems to have come about through over-diagnosis and treatment of tumours often too small to ever cause harm claim researchers in a study published online Feb 20th in JAMA Otolaryngology
Supposedly, cases of the disease have nearly tripled since 1975. In Europe post Chernobyl, there were cases diagnosed in the fallout path (down through Lyon, and into Wales, for example).
The researchers questioned whether the cancer needed such aggressive treatment. Some cancers grow so slowly, that researchers fear ‘overzealous screening leads to overzealous treatment’.
Thyroid cancer treatment usually entails surgery to remove the thyroid gland, followed by a lifetime of daily hormone pills.
"Our old strategy of looking as hard as possible to find cancer has some real side effects," said Dr. Gilbert Welch, co-author of the thyroid study and a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice.
Welch said patients "can no longer assume" that labelling a disease as cancer means treatment is necessary. "It’s a challenging rethinking," he added.
Welch and Dartmouth colleague Dr. Louise Davies analysed US government data from 1975 to 2009 and found thyroid cancers jumped from 5 cases per 100,000 people to 14 per 100,000. Most of that increase was in papillary thyroid
cancers, the most common and least deadly kind; those cases jumped from about three cases per 100,000 to more than 12 per 100,000.
The results suggest there is "an ongoing epidemic of thyroid cancer" nationwide, they said.
The new research echoes previous studies but "certainly raises some provocative questions," said Dr. Brian Burkey, a Cleveland Clinic head and neck cancer specialist. “Experts know that better detection methods including CT scans and ultrasound, have led to more thyroid cancers being diagnosed, but they don’t know which ones will become aggressive”, Burkey added.
"Thyroid cancer even if treated has a fairly high recurrence rate even if it doesn’t kill," he said.
The study authors believe oncologists should "openly share with patients the uncertainty surrounding small thyroid cancers — explaining that many will never grow and cause harm to a patient," but that it’s not possible to know for certain which ones are harmless.