Why can differentiated thyroid cancers be hard to detect?
- Histologically similar to normal
- Physiologically similar to normal
How do differentiated thyroid cancers differ from normal tissue?
- They secrete thyroglobulin
- They take up iodine to a greater extent
Which population of people have a particularly low incidence of differentiated thyroid cancer?
Lifestyle factors such as smoking and obesity increase risk of differentiated thyroid cancer
True or false?
An individual cannot really predispose themselves to this type of cancer
What can cause a rise in DTC cases?
(this will happen around 25 years after the incident)
How do DTCs often present?
- Palpable nodule in the neck - either part of the thyroid of a lymph node
- Pathological fractures
Cervical lymphadenopathy is associated most with which DTC?
Papillary thyroid carcinoma
Distant metastasis is most associated with which DTC and why?
Follicular thyroid carcinoma
Which investigations may be used for DTC?
- Excision of lymph nodes
- Pre-operative laryngography (if there is vocal cord palsy)
What are the three surgical options for DTC treatment?
- Thyroid lobectomy
- Sub-total thyroidectomy
- Total thyroidectomy
What is one postive aspect and one negative aspect to thyroid lobectomy?
Positive - Less invasive and lower mortality
Negative - Remaining thyroid poses cancer recurrence risk
What does a subtotal thyroidectomy involve?
Leaving 5-10% of the thyroid gland present during removal
What is the main issue with total thyroidectomy?
Risks post-operative complications
(e.g. recurrent laryngeal nerve palsy)
For high risk patients, which other treatment option may be used in DTC?
Why may hypocalcaemia develop post-operatively for a DTC?
Damage or accidental removal of parathyroid glands
In patients who have undergone subtotal or total thyroidectomy, what will be done 3-6 months post op?
Whole body iodine scan
In order for a whole body iodine scan to show up remaining tumour, or metastasis, which hormone must be high?
(these tumours are TSH driven)
How can TSH levels be boosted prior to a whole body iodine scan?
Recombinant human TSH (rhTSH) can be given as an injection
Why is the use of rhTSH in the patient's interest?
It can be used in conjunction with T3/4
No symptoms of hypothyroidism need be experienced as T3/4 do not need to be stopped this way
If differentiated thyroid cancer is found on a whole body iodine scan, what is the next stage in treatment?
250x dose (compared to scanning) of RAI is given to destroy cells
The patient is hospitalised in alead lined room
What are the main systemic side effects of RAI?
No major side effects
Salivary glands and throat may be sore
What does the follow up to RAI therapy involve?
Supressing TSH <0.1mU/L to minimise recurrence
Thyroxine can aid with this (must be < 25 however)
What can be used as a tumour marker in DTC?
What should the thyroglobulin levels be after RAI treatment?
They should be undetectable
In which patients is thyroglobulin not a useful tumour marker?
Patients with a thyroid lobectomy
Haf the thyroid gland remains to produce physiological thyroglobulin which masks any produced by a tumour
What is the main risk associated with RAI treatment?
Incidence of acute myeloid leukaemia is increased 50%
(1 : 25,000 down to 1 : 13,000)
What is the expected prognosis for DTC?
Best of all cancer excluding non-melanoma skin cancer
Recurrent DTC will likely present within what length of time post-treatment?
Why is recurrent DTC not "the end of the world"?
It is still very curable
(I-131 scan and RAI treament again)
Why is a rising thyroglobulin but negative I-131 whole body scan worrying?
Suggests de-differentiated thyroid cancer
This behaves like an anaplastic cancer