Incidence and Prevalence

There are four types of thyroid cancer: papillary, follicular (including Hürthle cell cancer),

medullary, and anaplastic. Papillary and follicular cancers are well differentiated, while anaplastic tumours are undifferentiated. The relative frequencies and mortality rates for each of these histological types of thyroid cancer are shown in Table 1.

The majority of thyroid cancers are composed of the two forms of well-differentiated cancer— papillary and follicular.^[1] Well-differentiated thyroid cancers progress slowly, are the most responsive to treatment, and have a very high survival rate. ^[1] The onset of papillary thyroid cancer tends to occur between ages 30 and 50 years. Follicular cancer tends to occur in patients who are somewhat older (>40 years of age) than patients who have papillary cancer. Follicular cancer is considered to be more aggressive than papillary cancer. In about one third of patients with follicular thyroid cancer, the tumour is minimally invasive and tends not to spread. In the remaining two thirds of patients, the follicular cancer is more invasive. It may grow into blood vessels and from there metastasize to distant areas, particularly the lungs and bones. ^[2] Hürthle cell cancer, an even more aggressive form of follicular cancer, generally occurs in people older than 60 years of age.

Although well-differentiated thyroid cancer is uncommon, the annual incidence rate throughout the world ranges from 0.5 to 10 cases per 100,000 people. ^[3] There is a twofold to fourfold higher incidence of new thyroid cancer cases in women than in men. ^[3] In Europe, thyroid cancer affects approximately 24,826 individuals annually, with an estimated mortality rate of 5,993 patients each year . ^[5] For individual country information please see table 2. ^[5] For the Regional Incidence and 5-Year prevalence see table 3.

References

1. Hay ID, Klee GG. Thyroid cancer diagnosis and management. Clin Lab Med. 1993;13:725-734.

2. Greenspan FS, Strewler GJ, eds. Basic & Clinical Endocrinology. 5th ed. Stamford, Conn: Appleton and Lange; 1997:253-256.

3. Schlumberger MJ. Papillary and follicular thyroid carcinoma. N Engl J Med. 1998;338:297-306.

4. Black RJ, Bray F, Ferlay J, et al. Cancer incidence and mortality in the European Union: cancer registry data and estimates of national incidence for 1990. Eur J Cancer. 1997;33:1075-1107.

5. J. Ferlay, F. Bray, P. Pisani and D.M. Parkin. GLOBOCAN 2000: Cancer Incidence, Mortality and Prevalence Worldwide, Version 1.0. Limited version available from:
URL: http://www-dep.iarc.fr/globocan/globocan.htm
Last updated on 03/02/2001
Last Accessed: March 11th 2003