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Head And Neck > Thyroid > Flashcards

Thyroid Flashcards

1
Q

What are the main histological subtypes of thyroid cancer? (In order of frequency?)

A

Papillary (75-85%)
Follicular (10-20%)
Poorly differentiated (5%)
Anaplastic (<2%)

Medullary (5-10%)
Others (lymphoma, mets, small cell)

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2
Q

What histopathological subtypes are classed as differentiated?

A

Papillary

Follicular

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3
Q

Where does medullary thyroid cancer originate?

A

In C cells (can secrete calcitonin)

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4
Q

What familial syndrome is medullary thyroid cancer associated with?

A

MEN2A or MEN2B
(20% of cases)

MEN2: autosomal dominant inherited disorder characterised by medullary thyroid cancer, parathyroid tumours and pheochromocytoma. MEN results from germ line mutations in the REt proto-oncogene.

MEN2B is less common than 2A and is characterised by more aggressive MTC (100% cases), pheo (50-%), mucosal neuromas (95-98%) and intestinal ganglion neuromas (40%). Hyperparathyroidism is absent (unlike 2A). Nearly all patients have a marfanoid habitus. Early total thyroidectomy is effective in preventing MTC.

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5
Q

Describe the T staging for thyroid cancer? (TNM8)

A

T1 <=2cm
T1a <=1cm. T1b 1-2cm
T2. >2cm <=4cm
T3a >4cm limited to thyroid
T3b. Any size with gross extrathyroidal extension
T4a beyond capsule and invading local tissues
T4b invades prevertebral fascia/encases carotid artery or mediastinal vessels

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6
Q

Describe the N staging for thyroid cancer?

A

N1a level VI nodes

N1b cervical/retropharyngeal/superior mediastinal nodes

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7
Q

How to investigate a thyroid mass?

A

Bloods
Hx and examination
USS
FNA

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8
Q

Describe the Ultrasound staging system of thyroid nodules

A

U1 - 5

U1 normal
U2 benign
U3 equivocal
U4 suspicious
U5 malignant
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9
Q

Describe the FNA grading system?

A

Thy 1-5

Thy 1 - non-diagnostic, need repeat
Thy2 - benign
Thy3A - atypical, can’t exclude malignancy and further Ix required
Thy3f - follicular neoplasm suspected, need diagnostic hemithyroidectomy
Thy4 - suspicious of malignancy - need diagnostic hemithyroidectomy
Thy5 - malignant - thyroidectomy

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10
Q

What are the definite indications for total thyroidectomy

A 
>4cm (>=T3)
Multi-focal
Extra thyroidal spread
Family history
Lymph node involvement/distant mets
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11
Q

Who should definitely be offered radioiodine remnant ablation?

A

Tumour >4cm
Any size with gross extrathyroid extension,
lateral neck nodes

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12
Q

Who should not get RAI adjuvantly?

A

Solitary <=1cm
Histology classical PTC or follicular variant of papillary or follicular ca
Minimally invasive
No invasion of thyroid capsule

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13
Q

How is iodine131 excreted?

A

75% excretion via urine

Should double flush toilet for 1 week
Consideration of practicalities for incontinent patients

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14
Q

What is the half life of iodine 131?

A

8 days

Effective half life 24h

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15
Q

What types of thyroid cancer is Iodine131 used in?

A

Differentiated (papillary or follicular)

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16
Q

What dose of radioiodine is used adjuvantly?

A

T1&T2 : 1.1 GBq

T3, T4, N1 : 3.5GBq

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17
Q

What should the TSH be during treatment?

A

> 30

TSH stimulation is given for 2 days pre treatment (thyrogen IM)

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18
Q

What dietary considerations should patients be advised about with Iodine131?

A

2/52 low iodine diet pre treatment

Not to have CT contrast for 8/52 prior and no amiodarone for a year prior to tx

19
Q

What are the acute side effects of iodine 131?

A

Sore throat
Neck swelling
Nausea
Bleeding/oedema in mets

20
Q

What should patients be advised about regarding pregnancy with iodine131

A

Avoid pregnant people for set time after treatment (up to 3/52)
Not to become pregnant for 6/12 or father a child within 4/12

21
Q

What are the late SE of iodine131?

A

1:20 risk of dry mouth

<1% risk of secondary malignancy

22
Q

What dose of I131 is used in metastatic/residual disease? And how frequent can doses be given?

A

5.5GBq

At least 6/12 apart

23
Q

What is the max cumulative dose of I131?

A

22GBq

24
Q

How long should patients avoid bloods/invasive procedures after receiving radioiodine?

A

1 month

Inform lab of urgent samples needed

25
Q

What advice should be given to breastfeeding patients prior to radioiodine

A

Stop breast feeding at least 8/52 prior to tx and don’t restart after treatment

Breast feeding risks iodine uptake in lactating breasts and increases long term risk of breast cancer

26
Q

What follow up should be done post ablation?

A

Residual/metastatic disease - SPECT scan 2-10 days post ablation

For non-metastatic patients: 
TSH suppression (TSH <0.1 until post tx scan), serum thyroglobulin and antibodies at 3/12

Dynamic risk stratification at 9/12

Then follow up every 6-12 months. Clinical exam of neck, TFTs and Tg (and antibodies). USS if Tg antibody positive. Tg should be <1 if rises, USS neck +- FNA and CT thorax. If normal - PET

27
Q

What is dynamic risk stratification?

A

Informs future TSH suppression, done at 9/12 post tx

USS and stimulated Tg

Low risk (aim TSH 0.3-2): Tg < 1, USS normal

Intermediate risk (aim TSH 0.1-0.5 for 5-10y then reassess): Tg 1-10, USS equivocal

High risk (TSH <0.1): Tg >10, USS abnormal

28
Q

What percentage of differentiated thyroid cancer develop mets?

A

7-23%

29
Q

What are the common sites of metastatic disease? (Differentiated)

A

Neck nodes, lung, bone

30
Q

What is the first treatment for metastatic disease?

A

Thyroidectomy

31
Q

Following thyroidectomy for metastatic disease (differentiated), what is first line treatment?

A

Radioiodine. This can be repeated if >6/12

32
Q

What should you consider when giving pre-radioiodine TSH stimulation in metastatic patients?

A

Prophylactic steroids to cover for tumour flare

33
Q

What is classed as radioiodine refractory disease?

A

At least 1 measurable lesion with no uptake on Iodine 131 scan
PD within 12/12 of iodine 131 despite uptake at the time
PD after 600mCi (3.7 GBq = 100mCi)

34
Q

What is the prognosis of radioiodine refractory disease?

A

MOS 2.5-3.5y

35
Q

If giving radioiodine with spinal mets. What should you consider?

A

Irradiating spine first as can cause oedema

36
Q

What dose of radiotherapy would you give for thyroid cancer?

A

60Gy in 30# to primary tumour and involved nodes

54Gy in 30# to selected regional nodes

Up to 64Gy to macroscopic residuum

Reserved for inoperable/non radioiodine avid

37
Q

What treatment options can be considered in radioiodine refractory disease?

A 
Surveillance
XRT
Surgery
Supportive care
Trials
TKIs - levantinib or sorafenib
38
Q

Would you give radioiodine to a metastatic anaplastic thyroid cancer?

A

No, no role for radioiodine.

39
Q

What is the median survival of anaplastic thyroid cancer?

A

7 months

40
Q

What are the treatment options for anaplastic thyroid cancer?

A

Very aggressive, often inoperable.

BSC
Palliative EBRT
Palliative chemo (carbo-taxol) - 15% RR
BRAF mutated disease - compassionate access programme - dabrafenib/trametinib if PS 0-1

41
Q

What blood marker should be checked for medullary thyroid cancer?

A

Calcitonin (NOT Tg)

CEA

42
Q

What adjuvant treatment is offered for medullary thyroid cancer?

A

No proven benefit for adjuvant treatment

No need for TSH suppression, just replace

43
Q

What should you screen for in medullary thyroid cancer?

A

Phaeochromocytoma

Genetics referral for RET

44
Q

What systemic treatment can be considered for metastatic medullary thyroid ca?

A

Cabozantinib 140mg OD.

Prolongs PFS (11.2m v 4m)
RR 30%

Head And Neck (8 decks)

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