Thyroid Cancer Flashcards
Normal Thyroid Follicle
Normal Follicular cells
Papillary thyroid carcinoma (4)
-large tightly packed cells
-clear nuclei( open chromatin)
-irregular membranes
-psuedoinclusions
epidemiology (4)
-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
Presentation (3)
Majority present with palpable nodules
Small percentage are chance findings on histological section of thyroidectomy tissue
Approximately 5% present with local or disseminated metastases
Papillary thyroid cancer (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%
Follicular carcinoma (5)
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
Investigation (5)
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
Clinical predictors of malignancy (6)
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
Operative management (4)
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
Surgical options (3)
Thyroid lobectomy with isthmusectomy
Sub-total thyroidectomy
Total thyroidectomy
Post-operative care (4)
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
Risks post-op (4)
AMES
A- Age
M- Metastases
E- Extent of primary tumour
S- Size of primary tumour
AMES low risk (3)
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%
AMES high risk (5)
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%
Thyroid lobectomy with isthmusectomy (3)
Papillary microcarcinoma ( < 1cm diameter)
Minimally invasive follicular carcinoma with capsular invasion only
Patients in AMES low risk group
Sub-total or total thyroidectomy (5)
DTC with extra-thyroidal spread
Bilateral / multifocal DTC
DTC with distant metastases
DTC with nodal involvement
Patients in AMES high risk group
Lymph node surgery (5)
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
Whole body Iodine scanning (7)
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
Thyroid Remnant Ablation (5)
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
Follow-up after TRA (7)
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”
Long term effects of TRA (3)
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
Thyroglobulin (3)
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
Recurrent disease (4)
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
Systemic Anti-Cancer Therapy (3)
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.
