What are the different histological types of thyroid cancer ?
- Papillary thyroid carcinoma (about 70%)
- Follicular thyroid carcinoma (about 15%)
- Poorly differentiated thyroid carcinoma (< 5%)
- Udifferentiated (anaplastic) thyroid cacinoma (< 5%)
- Medullary thyroid carcinoma (5-10%)
- others (lymphoproliferative neoplasias, metastases)
What do most differentiated thyroid cancers take up and secrete ? and what hormone drives them ?(hint think what drives normal thyroid function)
They take up iodine and secrete thyroglobulin
Driven by TSH
Do differentiated tumours indicate a better or worse prognosis than other solid tumours ?
A better prognosis
Differentiated thyroid cancers (DTC's) are 2-3 times more common in females and less common in afro Americans ? T/F?
Exposure to what predisposes patients to DTC's ?
Strong association with exposure to radiation
DTC's have No association with diet, other proven malignancies, family history, smoking or other lifestyle factors, except from clusters associated with nuclear incidents . T/F?
What do the majority of DTC's present with?
Approx 5% present with local (cervical lymphadenopathy) or disseminated metastases (usually presents as pathological fractures of long bones e.g. femur)
What is the commonest histo type of thyroid cancer ?
How does papillary thyroid cancer normally spread ?
•Tends to spread via lymphatics
•Can spread Haematogenously where it spreads to lungs, bone, liver and brain
What condition is papillary thyroid cancer linked with ?
What is the second most common histological type of thyroid cancer and how does it usually spread ?
•Incidence slightly higher in regions of relative iodine deficiency
•Tend to spread haematogenously
•Lymphatic spread relatively rare.
What is the prognosis of papillary and follicular thyroid cancer ?
Very good, 10 year mortality < 5%
When suspecting thyroid cancer what is the main investigation used to diagnose it ?
Ultrasound guided fine needle aspiration (US FNA)
When suspecting thyroid cancer what should you do if there is vocal cord palsy suspected clinically ?
What feautures point towards a potential thyroid cancer?
- New thyroid nodule age <20 or >50
- Nodule increasing in size
- lesion > 4cm in diameter
- History of head and neck irradiation
- Vocal cord palsy
What is the treatment of choice for thyroid cancer ?
Surgery - extent of surgery is controversial
What are the 3 main different surgical options for thyroid cancer ?
- Thyroid lobectomy with isthmusectomy
- Sub-total thyroidectomy – leaves 5-10% of gland
- Total thyroidectomy – higher risk of complications
In patients with thyroid cancer what is used to stratify the risk of patients post-op?
- A- Age
- M- Metastases
- E- Extent of primary tumour
- S- Size of primary tumour
What would class someone as a high and a low AMES risk patient ?
- Young patients men <40 women <50 with no metastases
Older patients with intrathyroidal papillary lesion or minimally invasive follicular lesion and primary tumour < 5cm and no distant metastases
- All patients with distant metastases
- Extrathyroidal disease in patients with papillary cancer
- Significant capsular invasion with follicular carcinoma
- Primary tumour > 5cm in older patients
In what patients can a Thyroid lobectomy with isthmusectomy be used in ?
- Papillary microcarcinoma ( < 1cm diameter)
- Minimally invasive follicular carcinoma with capsular invasion only
- Patients in AMES low risk group
Think used less commonly now because patients worry that if there was cancer in one lobe there will be cancer in the other
When is sub-total or total thyroidectomy done ?
- DTC with extra-thyroidal spread
- Bilateral / multifocal DTC
- DTC with distant metastases
- DTC with nodal involvement
- Patients in AMES high risk group
If there is lymph node involvement in patients with thyroid cancer what is done ?
•Patients with macrosopic lymph node disease should undergo nodal clearance
•Current practice in Tayside is for central compartment clearance and lateral lymph node sampling for papillary tumours
•Role in follicular cancer unclear, but current practice is to perform central lymph node clearance.
After thyroidectomy surgery what needs to be monitored ?
- If <2mmol/L then calcium replacement inititated
- If <1.8mmol/L or symptomatic then IV calcium given
When is whole body iodine scanning used ?
After sub-total or total thyroidectomys and also after Thyroid remnant ablation
T4 needs to be stopped 4 weeks prior and T3 therapy needs to be stopped 2 weeks prior to whole body iodine scan, what then makes rhSTH so good ?
When the thyroid gland has been removed and radioactive iodine given to destroy any remaining cancer cells, thyroglobulin should no longer be produced unless there are still cancer cells left in your body. This makes the thyroglobulin blood test a useful way of detecting any remaining papillary or follicular cancer cells. The blood test is often repeated every 6–12 months. You may also have radioactive iodine scans from time to time, to check whether there are any thyroid cancer cells in your body. Before a radioactive iodine scan you’ll need to stop taking thyroid hormone replacement tablets. If you are taking Page 2 of 3 Questions about cancer? Ask Macmillan 0808 808 00 00 www.macmillan.org.uk After treatment for thyroid cancer thyroxine (T4), you’ll need to stop taking it 4–6 weeks before the scan. Triiodothyronine (T3) tablets will need to be stopped 1–2 weeks before. This is done so that the body will produce enough thyroid-stimulating hormone (TSH) to make the tests as accurate as possible. TSH makes any thyroid cells, or thyroid cancer cells that may be left in your body, produce thyroglobulin and absorb radioactive iodine. Stopping the hormone replacement tablets will mean that your levels of thyroid hormones will get lower. As a result, you’ll begin to develop the symptoms of hypothyroidism, such as depression, weight gain, forgetfulness, decreased concentration and tiredness. This may affect your ability to drive or operate machinery. You can start taking your tablets again once the tests are finished. The symptoms should begin to reduce as the levels of thyroid hormones in your bloodstream increase. Recombinant human thyroid stimulating hormone (rhTSH) It may be possible to be treated with recombinant human TSH (or rhTSH) to overcome the problems of stopping your hormone replacement treatment. This man-made drug (also known as thyrotropin alfa or Thyrogen®) is similar to the TSH produced in your body. If you are given rhTSH you don’t need to stop taking your thyroid hormone replacement tablets, and won’t develop the symptoms of hypothyroidism. The drug rhTSH is given as an injection, usually into the muscle in your buttock. You’ll be given two injections, 24 hours apart. You can be given the radioactive iodine the next day if you are having a scan. The scan will then be done 48–72 hours later. The thyroglobulin blood test is done 72 hours after your second injection of rhTSH.
What is thyroid remnant ablation ?
Basically where the patient is pre-treated with rhTSH the given 2 or3 GBq capsule of I-131 to destroy any cancer cells
Are side effects of thyroid remnant ablation common and what are they?
Not common - Sialadenitis (swelling of salivary gland) and sore throat most noticeable ones
What is the follow-up after treatment with TRA?
- Repeat whole body scan performed to ensure uptake in thyroid bed is now <0.1%
- Usually patients maintained on T4
- Aim is to suppress TSH to <0.1mU/l and have FT4 below 25
What can measuring thyroglobulin be used as ?
A tumour marker
What is the main long-term effect of undergoing thyroid remnant ablation?
Doubles risk of leukaemia from 1 in 25000 to 1 in 13000 if they don’t have it and rely on surgery alone then 10 year survival about 75% rather than 95% with the gold standard of surgery TRA and follow up
How can recurrent DTC's be detected ?
By rising Tg, or by imaging such as whole body iodine scan
If a patient has rising Thyroglobin (Tg) but negative whole body iodine scan what imaging can be done to identify sites of disease and allow surgery / radiotherapy to be targeted?