differentiated thyroid cancer

Question 1

2 types of differentiated thyroid cancer

Answer 1

• papillary (80%)

- follicular

Question 2

what does differentiated mean

Answer 2

it is difficult to distinguish the cancerous cells from normal thyroid cells on histology

Question 3

differentiated thyroid cancers are driven by

Answer 3

TSH

Question 4

differentiated thyroid cancer secrete

Answer 4

thyroglobulin and take up radioactive iodine

Question 5

differentiated thyroid cancers are more common in

Answer 5

3x more common in woman and after radiation exposure

Question 6

after nuclear accidents such as chernobyl

Answer 6

the incidence in thyroid cancer increases exactly 25 years after the accident

Question 7

presentation

Answer 7

• nearly all present with a palpable thyroid nodule
• in a few cases it is an incidental finding on sectioning of thyroidectomy tissue
• in 5% of cases present with local or disseminated metastases

Question 8

investigations

Answer 8

• ultrasound guided fine needle aspirate

- if vocal nerve palsy clinically suspected (hoarseness) a laryngoscopy is carried out before surgery

Question 9

risk factors for a thyroid nodule being malignant rather than benign

Answer 9

• new thyroid nodule in someone under 20 or someone over 50
• nodule has increased in size
• lesion is greater than 4cm in diameter
• history of hear/ neck irradiation
• voice cord palsy

Question 10

management of differentiated thyroid cancer

Answer 10

surgery is the treatment of choice with post-surgical radioactive iodine ablation if AMES wish high

Question 11

3 surgical options

Answer 11

1. thyroid lobotomy with istmusectomy (rarely carried out now due to the high risk of recurrent and very difficult to monitor thyroglobulin levels for recurrence after)
2. subtotal thyroidectomy (removes most of the thyroid but leaves 5-10% to reduce the risk of damaging local structures)
3. total thyroidectomy (highest change of getting all the tumour but highest chance of damaging surround structures)

Question 12

post-surgery risk stratification uses the

Answer 12

AMES CRITREIS 
Age
Metastases
Extent of primary tumour 
Size of primary tumour

Question 13

Ames low risk

Answer 13

• age less than 40 for men age less than 50 for woman

- no evidence of metastases

Question 14

Ames high risk

Answer 14

• are greater than 40 for men and 50 for woman
• all patient with distant metastases
• significant capsular invasion in follicular cancer
• primary tumour is greater than 4cm

Question 15

lymph node clearance during surgery

Answer 15

• for papillary carcinomas the central lymph node compartment is cleared and the lateral compartment is biopsied
• for follicular carcinomas the central compartment is cleared and the lateral compartment is left along

Question 16

post-surgical management

Answer 16

• calcium levels checked wishin 24 hours:
  replace calcium is if falls below 2mmol/l, IV calcium if it falls below 1.8mmol/l due to risk of cardiac arrest
• patient discharged in levothyroxine to keep TSH levels on lower limit of normal

Question 17

AMES low risk patients

Answer 17

require no further management and are monitored yearly

Question 18

all ames high risk patients

Answer 18

get a whole body iodine scan 3-6 months after initial surgery, TSH levels must be high for the scan so the person taken rhTSH (recombinant human TSH) before the scan and is given iodine capsule

Question 19

if the iodine scan shows uptake

Answer 19

you proceed with radioactive thyroid remnant ablation

Question 20

radioactive iodine remnant abaltion

Answer 20

patient is in a lead lined room, given rhTSH and given a massive dose of iodine which is 250x that used for the scan, the cannot leave the room until there count rate is less than 500 counts per second

Question 21

the one issue with thyroid remnant ablation

Answer 21

it does increase the risk of acute myeloid leukaemia but the initial risk was tiny anyways and it doesn’t happen until 13 years after
it does NOT affect fertility, but 100% don’t be a fannnnnny and give it to a pregnant woman

Question 22

what is used as a tumour marked in differentiated thyroid cancer

Answer 22

thyroglobulin because differentiated thyroid cancer secretes thyroglobulin

Question 23

if Tg becomes elevated at any point during follow up

Answer 23

get a full body iodine scan again, and if there is still cancer you can try thyroid remnant ablation again

Question 24

new drugs that have just been licensed

Answer 24

sorafenib and lenvatinib for differentiated thyroid cancer which is refractory to thyroid remnant ablation