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
2
Q
How common is thyroid cancer compared to all other cancers?
A
It is a relatively uncommon malignancy
3
Q
What is the incidence of thyroid nodules in the general population?
A
Approx 5%
4
Q
What gender are thyroid nodules more common in?
A
Women (2.5 : 1 female to male ratio)
5
Q
What is the prevalence of thyroid cancer in a solitary nodule or in a multi-nodular thyroid?
A
10-20%
6
Q
What increases the prevalence of thyroid cancer in a solitary nodule or multi-nodular thyroid?
A
Irradiation to the neck
7
Q
What are the most common types of thyroid cancer in the young?
A
- Papillary
- Follicular
- Medullary
8
Q
What is the most common type of thyroid cancer in the elderly?
A
-Anaplastic
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
10
Q
What are the risk factors for thyroid cancer?
A
- Benign thyroid conditions
- Radiation exposure
11
Q
What benign thyroid conditions can increase the risk of thyroid cancer?
A
- Goitre
- Thyroiditis
- Thyroid adenomas
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
13
Q
What increases the risk of thyroid cancer in those exposed to radiation?
A
Low levels of iodine
14
Q
On what basis are thyroid cancers classified?
A
Morphologically
15
Q
What are the morphological classifications of thyroid cancer?
A
- Papillary
- Follicular
- Anaplastic
- Hurthle cell
- Medullary cell
- Lymphoma
16
Q
What morphological classifications of thyroid cancer are considered to be ‘differentiated’?
A
- Papillary
- Follicular
17
Q
What % of cases of thyroid cancer are differentiated thyroid cancers?
A
90%
18
Q
What mutations are associated with papillary thyroid carcinoma?
A
- BRAF
- Overexpression of cyclin D1
19
Q
What % of papillary thyroid carcinomas are associated with BRAF mutations?
A
40%
20
Q
What signalling pathway may be disrupted in papillary and anaplastic cancers?
A
pRb signalling pathway
21
Q
Why might the pRb signalling pathway be disrupted in anaplastic thyroid cancers?
A
Due to upregulation of E2F1
22
Q
What cells do papillary thyroid tumours arise from?
A
Thyroid follicular cells
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
24
Q
How big are papillary thyroid tumours?
A
They vary in size, from microscopic cancers to large cancers
25
What might large papillary thyroid tumours invade into?
- The thyroid capsule
| - Contiguous structures
26
How do papillary thyroid tumours metastasise?
They tend to invade the lymphatics
Vascular invasion and haematogenous spread is uncommon
27
Describe the spread of follicular carcinoma?
Although mostly encapsulated, it commonly has microscopic vascular and capsular invasion
28
Is there lymph node involvement in follicular thyroid carcinoma?
There is usually no lymph node involvement
29
What can follicular thyroid carcinoma be difficult to distinguish from?
It's benign counterpart, follicular adenoma
30
Why can follicular thyroid carcinoma be difficult to distinguish from follicular adenoma?
As the distinction is made based on the presence or absence of capsular or vascular invasion, which cannot be evaluated by FNA
31
What % of thyroid cancers are medullary thyroid cancers?
10%
32
What cells do medullary thyroid cancers arise from?
C-cells of the thyroid
33
What do medullary thyroid cancers secrete?
Calcitonin
34
What are the forms of medullary thyroid cancer, in terms of aetiology?
- Sporadic
| - Hereditary
35
What % of medullary thyroid cancers are the sporadic form?
80%
36
What % of patients with familial medullary thyroid cancer have a mutated RET proto-oncogene?
85%
37
What other condition is associated with a mutated RET proto-oncogene?
MEN 2A (multiple endocrine neoplasia type 2) - almost all people with the condition have the mutated gene
38
What % of thyroid cancer are anaplastic?
5%
39
What are the features of anaplastic thyroid carcinoma?
- High mitotic rate
| - More likely to invade local structures such as lymph nodes
40
How do most patients with thyroid cancer present?
- Painless lump in thyroid
| - Cervical or supraclavicular lymphadenopathy
41
Are patients presenting with thyroid cancer hypo-, eu-, or hyperthyroid?
Almost all patients are euthyroid
42
What are the features of the thyroid lump in thyroid cancer?
- Moves with swallowing and tongue protrusion
| - Usually firm and non-tender
43
What can produce a hoarse voice in thyroid cancer?
Compression of the recurrent laryngeal nerve
44
Are dysphagia and stridor common presentations of thyroid cancer?
No, they are rare
45
How can thyroid cancer cause dysphagia and stridor?
They result from a large tumour compressing the upper airway and oesophagus
46
What % of adults with papillary thyroid cancer present with regional lymph node metastasis?
Up to 40%
47
Where do distant metastasis most commonly occur in papillary thyroid cancer?
- Lungs
- Bones
- Other soft tissues
48
How might children with papillary thyroid cancer present?
With a solitary thyroid nodule
49
What is more common in children with papillary thyroid cancer, compared to adults?
Cervical node involvement is more common in children
50
What % of children and adolescents have lung involvement at the time of diagnosis of papillary thyroid cancer?
Up to 10%
51
How does sporadic medullary thyroid carcinoma present?
As a solitary thyroid mass
52
What proportion of patients with sporadic medullary thyroid carcinomas have metastases to cervical and mediastinal lymph nodes?
About half
53
What occurs at later stages of sporadic medullary thyroid carcinoma?
Distant metastasis to lungs, liver, bones, and adrenal glands
54
What might be a feature of advanced medullary thyroid carcinoma?
Secretory diarrhoea
55
What causes secretory diarrhoea in advanced medullary thyroid carcinoma?
It is secondary to calcitonin secretion
56
How is familial medullary thyroid carcinoma more likely to present?
As a bilateral, multifocal process, often with amyloid deposits
57
How might anaplastic thyroid tumours present?
May invade the skin, producing erythema and palpable nodules
58
What routine investigations should be done in thyroid cancer?
- Thyroid function tests
| - Thyroid isotope scanning
59
What is the use of a thyroid ultrasound scan in suspected thyroid cancer?
- Differentiate between solid and cystic lumps
| - Guide fine needle aspiration biopsy
60
What is the purpose of fine needle aspiration biopsy in suspected thyroid cancer?
Can provide cytological diagnosis
61
What is the limitation of fine needle aspiration biopsy in thyroid cancer?
Occasionally, the FNA sample is insufficient, and a surgical biopsy is required
62
What further staging investigations are done once thyroid cancer is confirmed?
- CXR
| - CT scan of neck and thorax
63
What can be used as an alternative to CT scanning in thyroid cancer?
MRI scanning
64
What imaging technique is still be evaluated in thyroid cancer?
PET/CT
65
What can PET/CT be useful for in thyroid cancer?
Assessing response to treatment
66
What should be measured in patients with medullary thyroid carcinoma?
Serum calcitonin
67
What is thyroglobulin normally produced by?
Follicular cells of the thyroid
68
When should thyroglobulin levels be undetectable in the serum?
Following a thyroidectomy
69
How can measuring thyroglobulin levels be useful?
Can help follow the course of papillary and follicular thyroid cancer
70
Can thyroid isotope scans differentiate a benign from a malignant nodule?
No
71
What is the use of thyroid isotope scan?
Can determine the probability that a thyroid nodule is cancerous based on the functional status of the nodule
72
How can thyroid isotope scans differentiate functioning and non-functioning thyroid nodules?
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
Do thyroid carcinomas occur in hot or cold nodules?
Most occur in cold nodules
74
What % of cold nodules are carcinomas?
10%
75
What does T describe in the staging of thyroid cancer?
Extent of tumour
76
What can the T categories contain in thyroid cancer?
Subdivisons - a and b
77
What does the 'a' subdivision indicate in the T staging of thyroid cancer?
Solitary lesion
78
What does the 'b' subdivision indicate in the T staging of thyroid cancer?
Multiple lesions
79
What is Tx in thyroid cancer?
Primary cancer cannot be assessed
80
What is T0 in thyroid cancer?
No evidence of cancer
81
What is T1 in thyroid cancer?
Tumour <1cm in greatest diameter
82
What is T2 in thyroid cancer?
Tumour >1cm, but <4cm in greatest diameter
83
What is T3 in thyroid cancer?
Tumour >4cm in greatest diameter
84
What is T4 in thyroid cancer?
Tumour outside of thyroid capsule, can be of any size
85
What is N0 in thyroid cancer?
No cancer in nearby lymph nodes
86
What is N1a in thyroid cancer?
Cancer in lymph nodes close to thyroid in neck
87
What lymph nodes are close to the thyroid in the neck?
- Pretracheal
- Paratracheal
- Prelarygneal
88
What is N1b in thyroid cancer?
Cancer in other lymph nodes in the neck
89
What lymph nodes in the neck would be considered N1b in thyroid cancer?
- Cervical
- Retropharyngeal
- Superior mediastinal
90
What is Mx in thyroid cancer?
Metastasis cannot be assessed
91
What is M0 in thyroid cancer?
No distant metastasis
92
What is M1 in thyroid cancer?
Distant metastasis present
93
What should be done after determining the site of thyroid cancer and extent of spread?
Patients should proceed to surgery
94
What surgery is required for patients with low-risk tumours confined to a single lobe?
Subtotal thyroidectomy with removal or the isthmus and affected lobe
95
What surgery is appropriate for the majority of those with thyroid cancer?
A total thyroidectomy
96
Does routine lymph node dissection have any impact on survival in thyroid cancer?
No, there is no evidence it does
97
Should lymph nodes be removed in thyroid cancer?
If they are affected, yes
98
What care needs to be taken during surgery for thyroid cancer?
Care to avoid damage to the parathyroid glands and recurrent laryngeal nerves
99
What treatment can be consider if patients have recurrent or residual thyroid cancer after surgery?
Radiotherapy
100
How can radiotherapy be administered in thyroid cancer?
- External beam radiotherapy
| - Radioiodine
101
What thyroid cancers is radioiodine commonly used for?
- Follicular
| - Papillary
102
What thyroid cancers is external beam radiotherapy more often used for?
Anaplastic and medullary cancers
103
Is chemotherapy used in the treatment of thyroid cancer?
Only when it has metastasised to other parts of the body
104
What is the limitation of chemotherapy in thyroid cancer?
It is generally not very effective
105
How are patients with thyroid cancer managed following treatment?
Thyroxine as thyroid replacement
106
What is the aim of thyroxine treatment after thyroid cancer?
Complete suppression of TSH
107
Why is complete suppression of TSH aimed for in thyroid cancer?
As TSH can be a driver for the development of recurrence
108
What is the prognosis for each type of thyroid cancer dependant on?
The extent of disease at presentation
109
What factors will significantly lower the survival of thyroid cancer?
- Involvement of lymph nodes
| - Distant metastasis
110
What age groups have a better prognosis of thyroid cancer?
Children have a good prognosis, and young people have a better outcome than the elderly
111
What is the overall 5 year survival of papillary thyroid cancer?
80%
112
What is the overall 5 year survival of follicular thyroid cancer?
60%
113
What is the overall 5 year survival of medullary thyroid cancer?
50%
114
What is the overall 5 year survival of anaplastic thyroid cancer?
10%
