Thyroid cancer has been ranked as the most frequently diagnosed cancer in South Korea. (Image courtesy of Yonhap)
SEOUL, Jan. 2 (Korea Bizwire) – For the third consecutive year, thyroid cancer has been ranked as the most frequently diagnosed cancer in South Korea, sparking renewed debate over the issue of overtreatment. The concern arises particularly in light of the fact that the five-year relative survival rate for patients diagnosed with thyroid cancer is reported to exceed 100%.
According to the ’2021 National Cancer Registry Statistics’ released by the Ministry of Health and Welfare (MOHW) and the Central Cancer Registry (National Cancer Center) on January 1, thyroid cancer had an incidence rate of 68.6 per 100,000 people, surpassing other cancers such as colorectal cancer (61.9), lung cancer (59.3), breast cancer (55.7), stomach cancer (55.3), prostate cancer (35), liver cancer (28.5), and cervical cancer (6.1).
The incidence rate of thyroid cancer, which was around 10% in 2000, surged to an average annual increase of 12.3% until 2009, reaching its peak in 2012 with 94.3 cases per 100,000 people. This abnormal surge led to criticisms of overtreatment.
One of the reasons for the criticism is the exceptionally high five-year relative survival rate of thyroid cancer patients, which hovers around 100%. A relative survival rate exceeding 100% implies that cancer patients have a higher survival rate than the general population.
The most recent statistics from 2021 show that the five-year relative survival rate for thyroid cancer patients stood at 100.1%, crossing the 100% mark.
In 2014, a group of doctors formed the ‘Doctors’ Coalition Against Overdiagnosis of Thyroid Cancer’ to address the issue of excessive diagnosis of thyroid cancer, particularly during health screenings, which they claimed was leading to a mass production of thyroid cancer patients.
Following the social attention drawn to the issue of overtreatment, the incidence rate of thyroid cancer decreased rapidly, dropping to 51.4% in 2015. However, the rate gradually increased again, reaching 60.8% in 2019, and continued to be the highest in the 2021 survey.
In response to this situation, Seo Hong-gwan, the director of the National Cancer Center and also the head of the National Cancer Registry, recently posted a critical message on social media, reiterating concerns over the overdiagnosis of thyroid cancer. Seo, who previously participated in the Doctors’ Coalition Against Overdiagnosis of Thyroid Cancer, emphasized that a survival rate exceeding 100% indicates that most cases of thyroid cancer do not require discovery or treatment. He cited a World Health Organization (WHO) report stating that 90% of thyroid cancer cases in Korea are overdiagnosed.
The National Cancer Center, following the 2015 national cancer screening guidelines, stated that “citizens without symptoms do not need to be screened for thyroid cancer.” The U.S. Department of Health and Human Services also advises against thyroid cancer screening for asymptomatic individuals, as the harm outweighs the benefits.
Seo also criticized medical institutions for unnecessarily including thyroid cancer diagnosis in private screening packages, leading to unnecessary ultrasonography and treatment, and ultimately to a waste of medical expenses and physical and mental distress for patients. He pointed out that while a minority of thyroid cancer patients do require aggressive treatment, the majority do not require diagnosis in the first place.
The National Cancer Center, through the National Cancer Information Center, explained that thyroid cancer refers to malignant nodules in the thyroid, with 5-10% of nodules in the thyroid being diagnosed as cancer. Untreated thyroid cancer can grow and invade surrounding tissues or metastasize to lymph nodes and distant sites, potentially leading to fatal outcomes.
M. H. Lee (mhlee@koreabizwire.com)
