Medullary Thyroid Cancer Incidence in China

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Medullary Thyroid Cancer Incidence in China: Why It’s Lower and What It Means

Thyroid cancer is one of the fastest-growing cancers globally, but its subtypes vary widely in how common and how dangerous they are. Medullary thyroid cancer (MTC)—a rare, aggressive form that starts in the thyroid’s C cells—makes up just 3% to 10% of all thyroid cancers worldwide. Yet in China, its proportion is even smaller: in Guangzhou, MTC fell from 2.03% of thyroid cancer cases in 2004 to 0.42% in 2013. Why is MTC less common in China compared to countries like the U.S. or U.K.? A 2019 study by researchers from Hubei University of Chinese Medicine and the University of Sassari explored this question, offering key insights into the trends and challenges.

What Is Medullary Thyroid Cancer (MTC)?

MTC is a neuroendocrine tumor that grows from the thyroid’s C cells—cells that produce calcitonin, a hormone that regulates calcium. Unlike the more common papillary thyroid cancer (PTC), which accounts for 80% to 90% of cases, MTC is more likely to spread early and has a worse prognosis.

Most MTC cases (75% to 80%) are sporadic—meaning they develop randomly. The rest are hereditary (hMTC), caused by mutations in the RET proto-oncogene. Hereditary MTC is linked to two syndromes: multiple endocrine neoplasia type 2A (MEN2A) and type 2B (MEN2B). For these families, genetic screening is critical to catch MTC early—but many in China can’t access or afford it.

The Challenge of Early MTC Detection

One of the biggest barriers to fighting MTC is how hard it is to diagnose early. Unlike other thyroid cancers, which often affect middle-aged adults, MTC typically strikes younger people (18–25 years old) and can stay asymptomatic for decades. Most patients don’t show symptoms until the tumor has grown large enough to press on nearby structures or spread. By the time MTC is diagnosed:

  • Nearly two-thirds of patients have lymph node metastases (in the neck or chest).
  • About 5% have distant spread to the liver, lungs, bones, or brain.

Worse, early-stage MTC often doesn’t show up on standard thyroid function tests. This leads to misdiagnoses:

  • A man initially treated for lung cancer was later found to have an MTC-linked RET mutation via genomic testing.
  • An 11-month-old with MEN2B was mislabeled with familial dysautonomia until age 6.

MTC Incidence: China vs. the West

MTC rates vary by country:

  • United States: 1% to 2% of thyroid cancers.
  • United Kingdom: 1% to 3% of thyroid cancers.
  • China: MTC’s share has dropped sharply. In Guangzhou, it fell from 2.03% in 2004 to 0.42% in 2013. Another study (Du et al., 2018) found PTC’s proportion rising significantly in Zhejiang Province between 1972 and 2014—while MTC’s share shrank.

Why Is MTC Less Common in China?

The researchers identified three key factors:

  1. More Papillary Thyroid Microcarcinoma (PTMC) Diagnoses
    PTMC—small PTC tumors (≤1cm)—makes up over 50% of new thyroid cancer cases in China. Since PTMC is so common, it “crowds out” MTC in statistical proportions. While PTMC is often low-risk, its overdiagnosis means MTC’s true incidence is harder to see.

  2. Limited Genetic Screening
    Hereditary MTC runs in families, but genetic testing for the RET mutation is not widely used in China. Many low-income families can’t afford it, and some patients avoid testing because they don’t want to know their risk. This means hereditary MTC cases are likely underdiagnosed.

  3. Lack of National Data
    China doesn’t have large-scale, national statistics on MTC. Without consistent data collection, it’s hard to measure the true burden of the disease.

What Can Be Done?

The study’s authors emphasize two priorities:

  • Early Detection: Improving access to genetic screening for high-risk families and training doctors to recognize MTC’s subtle signs.
  • Multidisciplinary Care: MTC treatment requires teamwork—endocrinologists, surgeons, radiologists, geneticists, and oncologists working together to catch tumors early and tailor care.

The Bottom Line

China’s lower MTC incidence isn’t just good news—it’s partly due to underdiagnosis and skewed proportions from more PTMC cases. To truly address MTC, China needs better genetic screening access, national data collection, and multidisciplinary care.

This research was published in the Chinese Medical Journal (2019) by Min Huang (Hubei University of Chinese Medicine), Giuseppe Fanciulli (University of Sassari), and colleagues.

doi:10.1097/CM9.0000000000000463

References:

  1. Pellegriti G, et al. Worldwide increasing incidence of thyroid cancer: update on epidemiology and risk factors. J Cancer Epidemiol 2013;2013:965212.
  2. Chen W, et al. Cancer statistics in China, 2015. CA Cancer J Clin 2016;66:115–132.
  3. Du L, et al. Thyroid cancer: trends in incidence, mortality and clinical-pathological patterns in Zhejiang Province, Southeast China. BMC Cancer 2018;18:291.
  4. Gordon EJ, et al. Genomic profiling reveals medullary thyroid cancer misdiagnosed as lung cancer. Case Rep Oncol 2018;11:399–403.
  5. Mass E, et al. Case report: multiple endocrine neoplasia type 2B misdiagnosed as familial dysautonomia. Eur J Paediatr Dent 2005;6:48–50.

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