Thyroid Cancer

Question 1

Normal Thyroid Follicle

Answer 1

Normal Follicular cells

Question 2

Papillary thyroid carcinoma (4)

Answer 2

-large tightly packed cells
-clear nuclei( open chromatin)
-irregular membranes
-psuedoinclusions

Question 3

epidemiology (4)

Answer 3

-incidence 2-3 higher in women
-Lower incidence in Afro-Americans
-exposure to radiation
-No association with diet, other proven malignancies, family history, smoking or other lifestyle factors

Question 4

Presentation (3)

Answer 4

Majority present with palpable nodules

Small percentage are chance findings on histological section of thyroidectomy tissue

Approximately 5% present with local or disseminated metastases

Question 5

Papillary thyroid cancer (5)

Answer 5

Commonest histological type

Tends to spread via lymphatics

Haematogenous spread to lungs, bone, liver and brain

Associated with Hashimoto’s thyroiditis

Prognosis generally very good with 10 year mortality < 5%

Question 6

Follicular carcinoma (5)

Answer 6

Second commonest histological type

Incidence slightly higher in regions of relative iodine deficiency

Tend to spread haematogenously

Lymphatic spread and therefore lymph node enlargement relatively rare.

Prognosis similar to that of papillary cancer

Question 7

Investigation (5)

Answer 7

Usually involves ultrasound guided FNA of the lesion

Can involve excision biopsy of lymph node

No role for isotope thyroid scan

No role for CT / MRI

If vocal cord palsy suspected clinically, for pre-operative laryngoscopy

Question 8

Clinical predictors of malignancy (6)

Answer 8

New thyroid nodule age <20 or >50
Male
Nodule increasing in size
lesion > 4cm in diameter
History of head and neck irradiation
Vocal cord palsy

Question 9

Operative management (4)

Answer 9

Surgery is treatment of choice

Extent of surgery required remains controversial

Literature is muddled- lack of RCT with long term follow-up, low incidence makes large trials by definition multi-centred etc

Much of current practice based on meta-analyses or retrospective single centre study

Question 10

Surgical options (3)

Answer 10

Thyroid lobectomy with isthmusectomy
Sub-total thyroidectomy
Total thyroidectomy

Question 11

Post-operative care (4)

Answer 11

Calcium checked within 24 hours

Calcium replacement initiated if corrected Calcium falls below 2 mmol/l

Intravenous calcium for calcium levels below 1.8 mmol/l or if symptomatic

Patient discharged on T3 or T4

Question 12

Risks post-op (4)

Answer 12

AMES

A- Age
M- Metastases
E- Extent of primary tumour
S- Size of primary tumour

Question 13

AMES low risk (3)

Answer 13

Younger patients ( men <40, women <50) with no evidence of metastases

Older patients with intrathyroidal papillary lesion or minimally invasive follicular lesion and primary tumour < 5cm and no distant metastases

20 year survival for AMES low risk group is claimed to be 99%

Question 14

AMES high risk (5)

Answer 14

All patients with distant metastases

Extrathyroidal disease in patients with papillary cancer

Significant capsular invasion with follicular carcinoma

Primary tumour > 5cm in older patients

20 year survival in AMES high risk is 61%

Question 15

Thyroid lobectomy with isthmusectomy (3)

Answer 15

Papillary microcarcinoma ( < 1cm diameter)

Minimally invasive follicular carcinoma with capsular invasion only

Patients in AMES low risk group

Question 16

Sub-total or total thyroidectomy (5)

Answer 16

DTC with extra-thyroidal spread
Bilateral / multifocal DTC
DTC with distant metastases
DTC with nodal involvement
Patients in AMES high risk group

Question 17

Lymph node surgery (5)

Answer 17

Controversial area

Lymph node spread at diagnosis depends on histology - papillary 35-60%, follicular 20%

Figures corrupted by sampling bias

Effect of routine lymph node clearance on long term survival unclear

Patients with macrosopic lymph node disease should undergo nodal clearance

Question 18

Whole body Iodine scanning (7)

Answer 18

Used in patients who have undergone sub-total or total thyroidectomy

Usually performed 3-6 months post-op

T4 stopped 4 weeks prior to scan

T3 stopped 2 weeks prior to scan

rhTSH is far better as no need to stop T3/T4

TSH should be greater than 20 for best results

Sensitivity determined by ensuring that TSH is elevated

Question 19

Thyroid Remnant Ablation (5)

Answer 19

Admitted to lead lined room with mains sewerage
Pre-treated with rhTSH as before

2 or3 GBq capsule of I-131 administered

Few side effects- sialadenitis, sore throat

Patient uses disposable cutlery, sheets and clothing stored until safe, little or no contact with nurses or visitors

Discharged when count rate <500cps at 1m

Question 20

Follow-up after TRA (7)

Answer 20

80% excreted in first 24 hours

Significant radiation protection regulations

Some evidence of overkill

Patient usually will undergo post-therapy scan prior to discharge

Normally, after completion of TRA and scans, patients maintained on T4

Aim is to suppress TSH to <0.1mU/l + have FT4 below 25

Thyroglobulin can be used as “tumour marker”

Question 21

Long term effects of TRA (3)

Answer 21

Small but significant increase in incidence of AML- mainly in patients with cumulative I-131 doses > 800 mCi and repeated therapy doses within 12 months.

No convincing evidence of increase in incidence of other solid tumours

No evidence of infertility or subsequent genetic abnormalities in children

Question 22

Thyroglobulin (3)

Answer 22

Results can be affected by thyroid status i.e. raised TSH is associated with elevation of Tg levels

Anti-thyroglobulin antibodies measured at same time as titre may affect interpretation of results.

Should be measured pre-op as not all subjects are secretors of Tg

Question 23

Recurrent disease (4)

Answer 23

Can be detected clinically, by rising Tg, or by imaging
Recurrence in cervical lymph nodes is commoner in papillary cancer

Haematogenous spread to lungs, bone or brain more common in follicular lesions

Usually, patients undergo whole body scan to determine ability of disease to take up iodine with a view to therapy

Recurrence rate is 30%, which implies that significant proportion of those with recurrent disease can be successfully treated

Question 24

Systemic Anti-Cancer Therapy (3)

Answer 24

SMC have approved Sorafenib and Lenvatinib for patients with DTC refractory to Radioactive Iodine therapy.

Some encouraging studies demonstrate improved progression-free survival

Small numbers of patients mean evidence base is slowly evolving.