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What is the most common type of thyroid cancer?
What is the approximate median age at diagnosis for thyroid cancer?
Which factor is most consistently linked to an increased risk of developing thyroid cancer?
In which type of geographical area is follicular thyroid carcinoma reported to be higher?
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What is the typical presentation for most differentiated thyroid cancers?
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What population does thyroid cancer show a significant female preponderance?
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Thyroid function tests are crucial for which aspect of thyroid cancer management?
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Which lifestyle factor has been reported to have a protective effect against thyroid cancer?
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What test is primarily used for the definitive diagnosis of thyroid carcinoma?
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Which imaging study is preferred for routine scanning due to delivering a lower radiation dose?
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In assessing differentiated thyroid cancers, which age and histology combination defines a low risk group?
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What is a key component of the management plan for differentiated thyroid carcinomas?
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Which high-risk variant of thyroid carcinoma is specifically mentioned in the content?
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Which system is commonly used for staging differentiated thyroid cancers?
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What is the main purpose of the chest radiograph in thyroid cancer evaluation?
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What treatment method is utilized for postoperative management of differentiated thyroid cancer cases?
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Study Notes
Thyroid Cancer
- Thyroid cancer is the most common endocrine cancer despite being rare.
- The annual incidence rate is higher in women than men.
- The global estimate shows 87,000 new cases worldwide yearly.
- Iceland and Hawaii have the highest incidence rates at 12-15 per 100,000 women and 3.9-4.7 per 100,000 men, respectively.
- Nigeria has a lower rate of 1.7 per 100,000 women and 0.8 per 100,000 men.
- The female to male ratio of thyroid cancer varies from 1.5:1 to 4:1, with the highest incidence in females between 25 and 50 years.
- Thyroid cancer is uncommon in childhood and adolescence, but incidence increases with age, with a median age at diagnosis being 45 to 55 years.
Types of Thyroid Cancer
- Approximately 80% of thyroid cancers are differentiated carcinomas, which are derived from follicular cells.
- These differentiated carcinomas are further classified into papillary and follicular cells.
Risk Factors
- Exposure to ionizing radiation, especially before puberty, is a significant risk factor for thyroid cancer.
- Increased incidence of differentiated thyroid carcinoma is associated with nuclear fallouts, atomic bombings, and radiation accidents.
- Follicular thyroid carcinoma is more common in iodine-deficient areas, while papillary carcinoma is prevalent in iodine-rich areas.
- Other factors include heredity and a history of benign thyroid disease.
- Protective effects have been observed with high consumption of fresh fish, certain vegetables, wine, and cigarette smoking, though the latter may be more related to the protective effects of alcohol in wine.
Presentation
- Most differentiated thyroid cancers present as an asymptomatic thyroid nodule.
- Cases may also involve localized thyroid gland involvement or lymph node metastasis.
Clinical Features
- Patients with thyroid cancer often present clinically euthyroid with normal serum thyrotropin concentration.
- Hyperthyroidism with thyrotoxic symptoms is uncommon.
Diagnostic Tests
- Thyroid function tests are crucial for management and follow-up of cases, although not diagnostic of thyroid carcinoma.
- Full blood count (FBC), serum electrolytes and urea (E&U), and liver function tests (LFT) are essential for assessment and preparation for therapy.
- Chest radiograph (CXR) is performed to rule out pulmonary or rib metastases.
- Radioiodine or technetium-99m imaging studies provide anatomical and functional evaluation of palpable nodules, detect occult or minimal cancer, identify metastatic deposits, and assess therapy effectiveness.
- Radioiodine-123 and technetium-99m are preferred over radioiodine-133 for routine scanning due to lower radiation dose.
- Radioiodine-131 is preferred for postoperative assessment and management of differentiated thyroid cancer cases.
- Thyroid ultrasonography is valuable for diagnosis and management of thyroid carcinoma.
- Ultrasound-guided fine needle aspiration cytology is the first choice procedure for definitive diagnosis.
- Computerized tomography (CT) scan assists in assessing the tumor and its extent.
Staging
- The TNM staging system is widely used and considers prognostic factors.
- About 80%-85% of differentiated thyroid cancers belong to the low-risk group, with a lower mortality rate.
- The low-risk group includes patients under 35 years of age, with papillary or follicular histology, primary tumor T1 or T2 (not penetrating capsule), and no distant or lymph node metastases.
- The high-risk group comprises tall-cell, columnar cell, and diffuse scleroding variants of papillary thyroid carcinoma, along with widely invasive, poorly differentiated, and Hurthle cell variants of follicular carcinoma.
Management
- Differentiated thyroid carcinomas require an integrated approach involving:
- Surgical excision
- Radioactive iodine therapy
- Thyroid hormone suppression of thyrotropin concentrations
- For anaplastic thyroid carcinomas:
- Radiotherapy
- Chemotherapy
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Description
This quiz explores the essential facts about thyroid cancer, its incidence rates globally, and the various types of thyroid cancer. It highlights the demographic differences in occurrence and important risk factors. Test your knowledge on one of the most prevalent endocrine cancers with a focus on its types and statistics.
