Scientists at the International Agency for Research on Cancer (IARC), in Lyons, France are saying that a huge percentage of thyroid cancer cases are in fact over-diagnosis. The number in the half-million, many are women, and they have been subjected to unneeded cancer treatments and surgery.
Published in the New England Journal of Medicine, this dire warning of an epidemic of thyroid cancer over-diagnosis comes from the IARC’s in-depth analysis of data gleaned from cancer registries from 1988 to 2007 in 12 countries including Australia, Denmark, England, Finland, France, Italy, Japan, Norway, South Korea, Scotland, Sweden, and the United States.
The IARC has put forth estimates of more than 470,000 women and 90,000 men being over-diagnosed with thyroid cancer. The majority of these cancers being small, low-risk papillary carcinomas. Yet patients were subjected to a total thyroidectomy as well as neck lymph node dissection and radiotherapy.
Over-diagnosis is being attributed to increased use of ultrasounds of the neck as well as CT scans and MRIs. New technology has detected high amounts of nonlethal diseases existing in the thyroid glands of otherwise healthy people. The US, France, and Italy had the highest rates of thyroid cancer over-diagnosis, but in South Korea, thyroid cancer became the most commonly diagnosed cancer in women. According to the IARC report, 90% of the cases from 2003 to 2007 were a result of over-diagnosis.
Individuals receiving this unnecessary treatment are at risk of vocal injury, permanent hypoparathyroidism, and risk factors associated with iodine treatment. The difference in incidence and mortality rates is far higher for thyroid cancer than any most cancers. For instance, women with thyroid cancer between 15 and 49 had an incidence to mortality ratio higher than 300, while women of the same age with breast cancer had an incidence to mortality ratio of 10.
Scientists are raising red flags warning that a mindset of systematic screening for thyroid cancer and overtreatment of nodules is detrimental. It is suggested that low-risk tumors simply be monitored and perhaps even reclassified and referred to by a term other than cancer, like what has happened in cervical precancer.