Thyroid Cancers: Considerations, Classifications, and Managements

Abstract

Rapidly increasing trend of thyroid cancer incidence has turned this disease into a global concern. An estimated number of 64,300 new cases of thyroid cancer occurred in men and women in 2016, which represents 3.8% of all new cancer cases of USA (htps://seer. cancer.gov/statfacts/html/thyro.html). Thus, there is a high possibility for every physician to encounter a case of thyroid cancer during his/her professional lifetime. In this chapter, we clariied epidemiology, diferent categories, and new approaches toward diagnosis and management of thyroid cancer.Keywords: thyroid cancer, epidemiology, diferentiated thyroid cancer, undiferentiated thyroid cancer, thyroid nodule Detailed epidemiology of thyroid cancerAs the most common endocrine cancer and ifth most common cancer in women, thyroid cancer includes approximately 1-1.5% of all new cases of cancer diagnosed annually in the USA based on previous data [1][2][3]. Thyroid cancer is more prevalent among women and those with positive family history of thyroid disease. Some prior studies have reported a worldwide increasing trend for thyroid cancer incidence in recent decades [4]. Annual percent change (APC) is a commonly used indicator for the assessment of changes in incidence. Based on US National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program, it has been reported 2.4% from 1980 to 1997 and 6.6% from 1997 to 2009 in both genders for thyroid cancer (data available at htp://seer.cancer.gov/statfacts/html/thyro.html).© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.According to [2009][2010][2011][2012][2013] data, the rate of new cases of thyroid cancer was 13.9 per 100,000 men and women per year (Figure 1). Table 1 summarizes number of new cases per 100,000 persons by race/ethnicity and sex. A recently published study on adolescent cancer incidence during 1975-2012 has reported a 2.12% increase for females and 1.59% for males between 15 and 19 years of age [5]. However, there is a study indicating that thyroid cancer incidence trend has slowed following release of American Thyroid Association (ATA) guideline in 2009 [6, 7]. It has been reported that overall thyroid cancer incidence had an increasing trend about 8% per year from 2000 to 2009. But APC showed a deceleration about 3% in men and 2.8% in women, which was conined to tumors less than 2.9 cm of size for women [7].Also, thyroid cancer-related mortality was estimated to consist 0.3% of all cancer-related deaths in 2016. A 5-year survival rate of 98.1% has been reported for thyroid cancer. Despite increasing trend of incidence, thyroid cancer mortality has a relatively stable rate about 0.5 cases per 100,000 persons both from 1973 to 2002 and 2009 to 2013 [8, 9].In conclusion, it seems that thyroid cancer has been following an ...

Micronuclei Formation upon Radioiodine Therapy for Well-Differentiated Thyroid Cancer: The Influence of DNA Repair Genes Variants

“…The age of DTC patients submitted to 131 I therapy ranged from 32 to 73 years, with a mean of 52.54 ± 11.62 years. As expected, female patients (88.5%, n = 23) greatly outnumbered male patients (11.5%, n = 3) and papillary carcinoma cases (PTC, 69.2%, n = 18) were also more frequent than follicular ones (FTC, 30.8%, n = 8), in agreement with gender and histotype distributions commonly reported for DTC [1,2,4]. Overall, 15.4% (n = 4) of patients were smokers.…”

“…TC incidence has been steadily increasing, over the last three decades [1], most likely because of "surveillance bias" and overdiagnosis resulting from increased detection of small stationary lesions of limited clinical relevance. A true rise in the number of TC cases (e.g., due to increasing exposure to ionizing radiation (IR) from medical sources) is, however, also possible [2][3][4].…”

“…The majority of DTC cases is indolent in nature, iodine-avid, and responds favorably to standard therapy. Overall prognosis is thus generally good, translating into high long-term survival and low disease-specific mortality [4].…”

“…Papillary (PTC) and follicular (FTC) thyroid carcinoma represent 85–90% and 5–10% of TC cases, respectively. These tumor histotypes retain their morphologic features, being often referred to as differentiated thyroid carcinoma (DTC) [ 3 , 4 ]. The best-established modifiable risk factor for DTC is IR exposure during childhood and adolescence (radioiodines including 131 I, X-radiation, γ-radiation) [ 2 , 3 , 4 , 5 ] and the standard treatment consists of surgical resection (total or near-total thyroidectomy) accompanied by post-thyroidectomy radioiodine (RAI) therapy and TSH suppression [ 3 , 4 ].…”

Thyroid Cancer: The Quest for Genetic Susceptibility Involving DNA Repair Genes

“…Papillary (PTC) and follicular (FTC) thyroid cancer, representing 85–90% and 5–10% of cases, respectively, are the most common histological varieties and are often collectively referred to as well-differentiated thyroid carcinoma (DTC). In contrast to anaplastic thyroid cancer (ATC), DTC prognosis is generally good, with high long-term survival and low disease-specific mortality [3,4].…”