differentiated thyroid cancer Flashcards
2 types of differentiated thyroid cancer
- papillary (80%)
- follicular
what does differentiated mean
it is difficult to distinguish the cancerous cells from normal thyroid cells on histology
differentiated thyroid cancers are driven by
TSH
differentiated thyroid cancer secrete
thyroglobulin and take up radioactive iodine
differentiated thyroid cancers are more common in
3x more common in woman and after radiation exposure
after nuclear accidents such as chernobyl
the incidence in thyroid cancer increases exactly 25 years after the accident
presentation
- 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
investigations
- ultrasound guided fine needle aspirate
- if vocal nerve palsy clinically suspected (hoarseness) a laryngoscopy is carried out before surgery
risk factors for a thyroid nodule being malignant rather than benign
- 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
management of differentiated thyroid cancer
surgery is the treatment of choice with post-surgical radioactive iodine ablation if AMES wish high
3 surgical options
- 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)
- subtotal thyroidectomy (removes most of the thyroid but leaves 5-10% to reduce the risk of damaging local structures)
- total thyroidectomy (highest change of getting all the tumour but highest chance of damaging surround structures)
post-surgery risk stratification uses the
AMES CRITREIS Age Metastases Extent of primary tumour Size of primary tumour
Ames low risk
- age less than 40 for men age less than 50 for woman
- no evidence of metastases
Ames high risk
- 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
lymph node clearance during surgery
- 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
post-surgical management
- 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
AMES low risk patients
require no further management and are monitored yearly
all ames high risk patients
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
if the iodine scan shows uptake
you proceed with radioactive thyroid remnant ablation
radioactive iodine remnant abaltion
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
the one issue with thyroid remnant ablation
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
what is used as a tumour marked in differentiated thyroid cancer
thyroglobulin because differentiated thyroid cancer secretes thyroglobulin
if Tg becomes elevated at any point during follow up
get a full body iodine scan again, and if there is still cancer you can try thyroid remnant ablation again
new drugs that have just been licensed
sorafenib and lenvatinib for differentiated thyroid cancer which is refractory to thyroid remnant ablation
