Thyroid Cancer : Definition, Etiopathogenesis, Types, Treatment And MCQs for NEET, GPAT, CSIR NET JRF

• 95% of all the primary thyroid cancers are carcinomas (means most common type of cancer).
• Carcinoma of the thyroid gland has four major morphologic types with distinctly different clinical behavior and variable prevalence. These are – the papillary, follicular, medullary and anaplastic carcinoma.

^{The above image is taken for education purpose only from cancer.gov}

ETIOPATHOGENESIS :-

Most important environmental factors implicated in the etiology of thyroid cancer is external radiation, and so to some extend, there is a role of TSH receptor and iodine excess.

A.] External Radiation : Exposure to high dose of external radiation is one of the most important and common factor which increases the risk of thyroid carcinoma. Exposure to radiation in children and young adults have higher risk of developing papillary carcinoma.

B.] Iodine excess and TSH : The region where endemic goiter is widespread, addition of iodine to diet has resulted in increased risk of papillary carcinoma.

TYPES :-

Four morphological forms of carcinoma are as follows :-

A.] PAPILLARY THYROID CARCINOMA : Papillary carcinoma is the most common type of thyroid carcinoma. It occurs at all ages in children as well as in adults. The tumor has high prevalence in females than men. It is an slow growing malignant tumor. The prognosis of papillary carcinoma depends upon either the tumor is pure papillary or mixed papillary – follicular carcinoma.

B.] FOLLICULAR THYROID CARCINOMA : Follicular carcinoma is the other common type of thyroid cancer, next only to papillary carcinoma and comprises about 10 – 20% of all the thyroid carcinomas. It is common in middle and old age and has preponderance in females. The tumor is slow – growing but more rapid then papillary carcinoma.

C.] MEDULLARY THYROID CARCINOMA : It is less frequent types derived from parafolloicular or C – cell present in the thyroid and comprises about 5 % of the thyroid carcinoma. It is equally common in men and women. There are 3 – distinctive features which distinguish medullary carcinoma from other thyroid carcinoma and they are – familial occurrence, secretion of calcitonin and other peptides, and amyloid stroma.

D.] ANAPLASTIC CARCINOMA : Anaplastic carcinoma of the thyroid comprises less than 5 % of all the thyroid cancers and is one of the most malignant tumor in humans. This tumor is found in old age and is very common in females than men. This tumor is widely aggressive and rapidly growing.

^{The above image is taken for education purpose only from verywellhealth.com}

TREATMENT :-

Treatment for thyroid carcinoma are as follows :

• By performing thyroidictomy (i.e; removing all or most of the thyroid), by thyroid lobectomy or by lymph node dissection.
• Also after having thyroidectomy, patients are advised to take medications like levothyroxine (Levoxyl, Synthroid)
• Also sometimes, radioactive iodine therapy is also given.

Below are the list of Approved Drugs for Thyroid Cancer Treatment

• Cabozantinib-S-Malate
• Vandetanib
• Cabozantinib-S-Malate
• Dabrafenib Mesylate
• Doxorubicin Hydrochloride
• Lenvatinib Mesylate
• Lenvatinib Mesylate
• Trametinib
• Sorafenib Tosylate
• Selpercatinib
• Selpercatinib
• Sorafenib Tosylate
• Dabrafenib Mesylate
• Trametinib
• Vandetanib

MULTIPLE CHOICE QUESTIONS :-

1.] Which is the most common type of thyroid carcinoma ?

a. Follicular carcinoma

b. Papillary carcinoma

c. Medullary carcinoma

d. Anaplastic carcinoma

2.] Which thyroid cancer is most likely to result from exposure of radiation in childhood ?

a. Medullary thyroid carcinoma

b. Follicular carcinoma

c. Papillary carcinoma

d. Anaplastic carcinoma

3.] MC thyroid cancer is ?

a. Papillary carcinoma

b. Follicular carcinoma

c. Medullary carcinoma

d. Anaplastic carcinoma

4.] Which of the following gene defect is associated with developmental of medullary carcinoma of thyroid ?

a. RET Proto – oncogene

b. FAP gene

c. Rb gene

d. BRCA 1 gene

5.] Medullary carcinoma of the thyroid is associated with which of the following syndrome ?

a. MEN I

b. MEN II

c. Li – Fraumini syndrome

d. Hashimoto’s thyroiditis

6.] The expression of the following oncogene is associated with a high incidence of medullary carcinoma of thyroid ?

a. p53

b. Her2neu

c. RET Proto – oncogene

d. Rb gene

7.] Which of the following histological type of carcinoma thyroid most commonly meta sizes to lymph node ?

a. Medullary

b. Anaplastic

c. Papillary

d. Follicular

8.] Oncocytes are found in all of the following except ?

a. Thyroid

b. Pancreas

c. Pituitary

d. Pineal gland

9.] Psammoma bodies are seen in all except ?

a. Papillary carcinoma of thyroid

b. Papillary adenoma of colon

c. Meningioma

d. Papillary cancer of the ovary

10.] Which thyroid carcinoma is C – cell origin ?

a. Medullary carcinoma

b. Follicular carcinoma

c. Papillary carcinoma

d. Anaplastic carcinoma

SOLUTIONS :-

1.] (b) Papillary carcinoma

2.] (c) Papillary carcinoma

3.] (a) Papillary carcinoma

4.] (a) RET Proto – oncogene

5.] (b) MEN II

6.] (c) RET Proto oncogene

7.] (c) Papillary

8.] (d) Pineal body

9.] (b) Papillary adenoma of colon

10.] (a) Medullary carcinoma

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REFERENCES :-

1.] Textbook Of Pathology By Harsh Mohan; 7th edition; Page no. 801 – 805.

2.] Robbin’s Basic Pathology; 5th edition; Page no. 1137 – 1142.