Thyroid Cancer Flashcards

1
Q

How common is thyroid cancer compared to other endocrine cancers?

A

It is the most common cancer of the endocrine system

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2
Q

How common is thyroid cancer compared to all other cancers?

A

It is a relatively uncommon malignancy

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3
Q

What is the incidence of thyroid nodules in the general population?

A

Approx 5%

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4
Q

What gender are thyroid nodules more common in?

A

Women (2.5 : 1 female to male ratio)

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5
Q

What is the prevalence of thyroid cancer in a solitary nodule or in a multi-nodular thyroid?

A

10-20%

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6
Q

What increases the prevalence of thyroid cancer in a solitary nodule or multi-nodular thyroid?

A

Irradiation to the neck

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7
Q

What are the most common types of thyroid cancer in the young?

A
  • Papillary
  • Follicular
  • Medullary
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8
Q

What is the most common type of thyroid cancer in the elderly?

A

-Anaplastic

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9
Q

What geographical locations have a higher incidence of thyroid cancer?

A

Regions that were exposed to the Chernobyl disaster, or Japanese populations following atomic bomb detonations

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10
Q

What are the risk factors for thyroid cancer?

A
  • Benign thyroid conditions

- Radiation exposure

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11
Q

What benign thyroid conditions can increase the risk of thyroid cancer?

A
  • Goitre
  • Thyroiditis
  • Thyroid adenomas
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12
Q

What might cause radiation exposure to the thyroid?

A
  • Treatment for childhood cancer

- High levels after environmental incidents, such as the Chernobyl disaster

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13
Q

What increases the risk of thyroid cancer in those exposed to radiation?

A

Low levels of iodine

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14
Q

On what basis are thyroid cancers classified?

A

Morphologically

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15
Q

What are the morphological classifications of thyroid cancer?

A
  • Papillary
  • Follicular
  • Anaplastic
  • Hurthle cell
  • Medullary cell
  • Lymphoma
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16
Q

What morphological classifications of thyroid cancer are considered to be ‘differentiated’?

A
  • Papillary

- Follicular

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17
Q

What % of cases of thyroid cancer are differentiated thyroid cancers?

A

90%

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18
Q

What mutations are associated with papillary thyroid carcinoma?

A
  • BRAF

- Overexpression of cyclin D1

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19
Q

What % of papillary thyroid carcinomas are associated with BRAF mutations?

A

40%

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20
Q

What signalling pathway may be disrupted in papillary and anaplastic cancers?

A

pRb signalling pathway

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21
Q

Why might the pRb signalling pathway be disrupted in anaplastic thyroid cancers?

A

Due to upregulation of E2F1

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22
Q

What cells do papillary thyroid tumours arise from?

A

Thyroid follicular cells

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23
Q

Describe the distribution of papillary thyroid tumours

A

They are unilateral in most cases, and are often multifocal within a single thyroid lobe

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24
Q

How big are papillary thyroid tumours?

A

They vary in size, from microscopic cancers to large cancers

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25
Q

What might large papillary thyroid tumours invade into?

A
  • The thyroid capsule

- Contiguous structures

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26
Q

How do papillary thyroid tumours metastasise?

A

They tend to invade the lymphatics

Vascular invasion and haematogenous spread is uncommon

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27
Q

Describe the spread of follicular carcinoma?

A

Although mostly encapsulated, it commonly has microscopic vascular and capsular invasion

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28
Q

Is there lymph node involvement in follicular thyroid carcinoma?

A

There is usually no lymph node involvement

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29
Q

What can follicular thyroid carcinoma be difficult to distinguish from?

A

It’s benign counterpart, follicular adenoma

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30
Q

Why can follicular thyroid carcinoma be difficult to distinguish from follicular adenoma?

A

As the distinction is made based on the presence or absence of capsular or vascular invasion, which cannot be evaluated by FNA

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31
Q

What % of thyroid cancers are medullary thyroid cancers?

A

10%

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32
Q

What cells do medullary thyroid cancers arise from?

A

C-cells of the thyroid

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33
Q

What do medullary thyroid cancers secrete?

A

Calcitonin

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34
Q

What are the forms of medullary thyroid cancer, in terms of aetiology?

A
  • Sporadic

- Hereditary

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35
Q

What % of medullary thyroid cancers are the sporadic form?

A

80%

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36
Q

What % of patients with familial medullary thyroid cancer have a mutated RET proto-oncogene?

A

85%

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37
Q

What other condition is associated with a mutated RET proto-oncogene?

A

MEN 2A (multiple endocrine neoplasia type 2) - almost all people with the condition have the mutated gene

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38
Q

What % of thyroid cancer are anaplastic?

A

5%

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39
Q

What are the features of anaplastic thyroid carcinoma?

A
  • High mitotic rate

- More likely to invade local structures such as lymph nodes

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40
Q

How do most patients with thyroid cancer present?

A
  • Painless lump in thyroid

- Cervical or supraclavicular lymphadenopathy

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41
Q

Are patients presenting with thyroid cancer hypo-, eu-, or hyperthyroid?

A

Almost all patients are euthyroid

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42
Q

What are the features of the thyroid lump in thyroid cancer?

A
  • Moves with swallowing and tongue protrusion

- Usually firm and non-tender

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43
Q

What can produce a hoarse voice in thyroid cancer?

A

Compression of the recurrent laryngeal nerve

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44
Q

Are dysphagia and stridor common presentations of thyroid cancer?

A

No, they are rare

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45
Q

How can thyroid cancer cause dysphagia and stridor?

A

They result from a large tumour compressing the upper airway and oesophagus

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46
Q

What % of adults with papillary thyroid cancer present with regional lymph node metastasis?

A

Up to 40%

47
Q

Where do distant metastasis most commonly occur in papillary thyroid cancer?

A
  • Lungs
  • Bones
  • Other soft tissues
48
Q

How might children with papillary thyroid cancer present?

A

With a solitary thyroid nodule

49
Q

What is more common in children with papillary thyroid cancer, compared to adults?

A

Cervical node involvement is more common in children

50
Q

What % of children and adolescents have lung involvement at the time of diagnosis of papillary thyroid cancer?

A

Up to 10%

51
Q

How does sporadic medullary thyroid carcinoma present?

A

As a solitary thyroid mass

52
Q

What proportion of patients with sporadic medullary thyroid carcinomas have metastases to cervical and mediastinal lymph nodes?

A

About half

53
Q

What occurs at later stages of sporadic medullary thyroid carcinoma?

A

Distant metastasis to lungs, liver, bones, and adrenal glands

54
Q

What might be a feature of advanced medullary thyroid carcinoma?

A

Secretory diarrhoea

55
Q

What causes secretory diarrhoea in advanced medullary thyroid carcinoma?

A

It is secondary to calcitonin secretion

56
Q

How is familial medullary thyroid carcinoma more likely to present?

A

As a bilateral, multifocal process, often with amyloid deposits

57
Q

How might anaplastic thyroid tumours present?

A

May invade the skin, producing erythema and palpable nodules

58
Q

What routine investigations should be done in thyroid cancer?

A
  • Thyroid function tests

- Thyroid isotope scanning

59
Q

What is the use of a thyroid ultrasound scan in suspected thyroid cancer?

A
  • Differentiate between solid and cystic lumps

- Guide fine needle aspiration biopsy

60
Q

What is the purpose of fine needle aspiration biopsy in suspected thyroid cancer?

A

Can provide cytological diagnosis

61
Q

What is the limitation of fine needle aspiration biopsy in thyroid cancer?

A

Occasionally, the FNA sample is insufficient, and a surgical biopsy is required

62
Q

What further staging investigations are done once thyroid cancer is confirmed?

A
  • CXR

- CT scan of neck and thorax

63
Q

What can be used as an alternative to CT scanning in thyroid cancer?

A

MRI scanning

64
Q

What imaging technique is still be evaluated in thyroid cancer?

A

PET/CT

65
Q

What can PET/CT be useful for in thyroid cancer?

A

Assessing response to treatment

66
Q

What should be measured in patients with medullary thyroid carcinoma?

A

Serum calcitonin

67
Q

What is thyroglobulin normally produced by?

A

Follicular cells of the thyroid

68
Q

When should thyroglobulin levels be undetectable in the serum?

A

Following a thyroidectomy

69
Q

How can measuring thyroglobulin levels be useful?

A

Can help follow the course of papillary and follicular thyroid cancer

70
Q

Can thyroid isotope scans differentiate a benign from a malignant nodule?

A

No

71
Q

What is the use of thyroid isotope scan?

A

Can determine the probability that a thyroid nodule is cancerous based on the functional status of the nodule

72
Q

How can thyroid isotope scans differentiate functioning and non-functioning thyroid nodules?

A

Thyroid nodules that concentrate the radioiodine (hot nodules) represent functioning nodules.
Thyroid nodules that do not concentrate the iodine (cold nodules) are non-functioning, and are more likely to be cancer

73
Q

Do thyroid carcinomas occur in hot or cold nodules?

A

Most occur in cold nodules

74
Q

What % of cold nodules are carcinomas?

A

10%

75
Q

What does T describe in the staging of thyroid cancer?

A

Extent of tumour

76
Q

What can the T categories contain in thyroid cancer?

A

Subdivisons - a and b

77
Q

What does the ‘a’ subdivision indicate in the T staging of thyroid cancer?

A

Solitary lesion

78
Q

What does the ‘b’ subdivision indicate in the T staging of thyroid cancer?

A

Multiple lesions

79
Q

What is Tx in thyroid cancer?

A

Primary cancer cannot be assessed

80
Q

What is T0 in thyroid cancer?

A

No evidence of cancer

81
Q

What is T1 in thyroid cancer?

A

Tumour <1cm in greatest diameter

82
Q

What is T2 in thyroid cancer?

A

Tumour >1cm, but <4cm in greatest diameter

83
Q

What is T3 in thyroid cancer?

A

Tumour >4cm in greatest diameter

84
Q

What is T4 in thyroid cancer?

A

Tumour outside of thyroid capsule, can be of any size

85
Q

What is N0 in thyroid cancer?

A

No cancer in nearby lymph nodes

86
Q

What is N1a in thyroid cancer?

A

Cancer in lymph nodes close to thyroid in neck

87
Q

What lymph nodes are close to the thyroid in the neck?

A
  • Pretracheal
  • Paratracheal
  • Prelarygneal
88
Q

What is N1b in thyroid cancer?

A

Cancer in other lymph nodes in the neck

89
Q

What lymph nodes in the neck would be considered N1b in thyroid cancer?

A
  • Cervical
  • Retropharyngeal
  • Superior mediastinal
90
Q

What is Mx in thyroid cancer?

A

Metastasis cannot be assessed

91
Q

What is M0 in thyroid cancer?

A

No distant metastasis

92
Q

What is M1 in thyroid cancer?

A

Distant metastasis present

93
Q

What should be done after determining the site of thyroid cancer and extent of spread?

A

Patients should proceed to surgery

94
Q

What surgery is required for patients with low-risk tumours confined to a single lobe?

A

Subtotal thyroidectomy with removal or the isthmus and affected lobe

95
Q

What surgery is appropriate for the majority of those with thyroid cancer?

A

A total thyroidectomy

96
Q

Does routine lymph node dissection have any impact on survival in thyroid cancer?

A

No, there is no evidence it does

97
Q

Should lymph nodes be removed in thyroid cancer?

A

If they are affected, yes

98
Q

What care needs to be taken during surgery for thyroid cancer?

A

Care to avoid damage to the parathyroid glands and recurrent laryngeal nerves

99
Q

What treatment can be consider if patients have recurrent or residual thyroid cancer after surgery?

A

Radiotherapy

100
Q

How can radiotherapy be administered in thyroid cancer?

A
  • External beam radiotherapy

- Radioiodine

101
Q

What thyroid cancers is radioiodine commonly used for?

A
  • Follicular

- Papillary

102
Q

What thyroid cancers is external beam radiotherapy more often used for?

A

Anaplastic and medullary cancers

103
Q

Is chemotherapy used in the treatment of thyroid cancer?

A

Only when it has metastasised to other parts of the body

104
Q

What is the limitation of chemotherapy in thyroid cancer?

A

It is generally not very effective

105
Q

How are patients with thyroid cancer managed following treatment?

A

Thyroxine as thyroid replacement

106
Q

What is the aim of thyroxine treatment after thyroid cancer?

A

Complete suppression of TSH

107
Q

Why is complete suppression of TSH aimed for in thyroid cancer?

A

As TSH can be a driver for the development of recurrence

108
Q

What is the prognosis for each type of thyroid cancer dependant on?

A

The extent of disease at presentation

109
Q

What factors will significantly lower the survival of thyroid cancer?

A
  • Involvement of lymph nodes

- Distant metastasis

110
Q

What age groups have a better prognosis of thyroid cancer?

A

Children have a good prognosis, and young people have a better outcome than the elderly

111
Q

What is the overall 5 year survival of papillary thyroid cancer?

A

80%

112
Q

What is the overall 5 year survival of follicular thyroid cancer?

A

60%

113
Q

What is the overall 5 year survival of medullary thyroid cancer?

A

50%

114
Q

What is the overall 5 year survival of anaplastic thyroid cancer?

A

10%