Thyroid carcinoma is the most common endocrine malignancy, with an annual incidence of 3.5 per 100,000 in the UK. Differentiated thyroid carcinomas have high 10-year survival rates of 80-90% for middle-aged adults, but recurrence rates of 10-15% are possible. Diagnosis is usually via fine needle aspiration biopsy of thyroid nodules, with surgery the main treatment depending on tumor size, involvement of lymph nodes, and histological subtype. Long-term monitoring of serum thyroglobulin levels and thyroid-stimulating hormone levels is important for screening for recurrence.
Incidence Most commonEndocrine malignancy (BUT only 1 % of ALL malignancies) 2001 1,200 new cases in England & Wales Annual Incidence in UK 3.5 per 100,000 ♀ 1.3 per 100,000 ♂
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Everything to gainfrom diagnosis 80-90 % 10 year survival rate for middle-aged adults with differentiated thyroid Ca BUT 5-20 % local recurrence 10-15 % distant metastases 9 % die of their disease
High risk patientsOlder age esp after age 40 yrs Male Poorly differentiated Increased size Degree of vascular invasion Extrathyroidal invasion Metastases Papillary better than follicular (?)
Risk factors forthyroid Ca Hx neck irradiation in childhood Endemic goitre Hashimoto’s thyroiditis (lymphoma) FH / personal Hx of thyroid adenoma FAP Familial thyroid Ca Cowden’s syndrome Exposure to nuclear fallout (Chernobyl)
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Presentation Thyroid noduleNewly discovered Recent increase in size of pre-existing nodule HOWEVER – 95 % benign Clinically present in 10 % ♀ & 2 % ♂ Prevalence as high as 50 % on U/S (!)
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Who to refer?Nodules can be managed in primary care IF: NOT changed for years Asymptomatic, < 1 cm discovered coincidentally on imaging AND no other worrying features/RFs Non-urgent referrals Abnormal TFTs Sudden onset of pain in a thyroid lump (likely to have bled into a benign thyroid cyst) New presentation / slow increase in size over months
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Urgent referrals Unexplainedhoarseness / voice change assocd with goitre Nodule in a child Cervical lymphadenopathy Rapidly enlarging and painless (over weeks) Typical of anaplastic and lymphomas Emergency same day referral for stridor Referrals See within 2/52 in secondary care Decision to treat should be made within 31/7
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Examination Inspection &palpation of the neck Thyroid exam Lymphadenopathy Record pulse & BP Full examination if any features of concern
Investigation TFTs Fineneedle aspiration cytology (FNAC) with / without U/S guidance Consider Thyroid AutoAbs MRI / CT If limits of goitre cannot be determined clinically Fixed tumours Haemoptysis DO NOT USE IODINATED CONTRAST MEDIA Use gadolinium-enhanced MRI Basal plasma calcitonin levels If MTC suspected Flow volume loop studies If upper airways obstruction suspected Core biopsy If tissue diagnosis difficult by FNAC No place for radioisotope studies or excisional biopsy
FNAC Can bereadily carried out without U/S guidance if lesion is palpable Can also be used for suspicious lymph nodes All material aspirated should be sent to the lab WITHOUT fixation Should be reported by a cytopathologist Cannot always make diagnosis of malignancy alone Cases should be discussed at MDT
Thy Classification ClassificationHistology Action Thy 1 Non-diagnostic Repeat FNAC (Unless cyst aspirated to dryness) Thy 2 Non-neoplastic Two non-neoplastic results 3-6/12 apart advised Thy 3 (i) Follicular lesion / suspected neoplasm Some cases will be hyperplastic nodules Surgical removal of the lobe. Completion thyroidectomy may be necessary if histology malignant Thy 3 (ii) Worrying features but cells too scanty to qualify for Thy 4 Discuss in MDT Repeat FNAC advised Thy 4 Suspicious of malignancy but not diagnostic Surgical intervention advised Thy 5 Diagnostic of malignancy Surgical intervention Consider radioT, chemoT
Prognostic scoring systemsMain two used: TNM & MACIS TNM T umour size N ode metastases M etastases (distant) MACIS M etastases A ge at presentation C ompleteness of surgical resection I nvasion (extrathyroidal) S ize All scoring systems emphasise age & size
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TNM classification ofthyroid Ca Primary tumour pT1 Intrathyroidal ≤ 1 cm pT2 Intrathyroidal > 1-4 cm pT3 Intrathyroidal > 4 cm pT4 Any size extending beyond thyroid capsule pTX Primary tumour cannot be assessed Regional lymph nodes (cervical or upper mediastinal) N0 No nodes N1 Regional nodes involved N1a Ipsilateral cervical N1b Bilateral, midline or contralateral cervical nodes or mediastinal nodes NX Nodes cannot be assessed Distant metastases M0 No mets M1 Distant mets MX Mets cannot be assessed
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Papillary or FollicularCa staging < 45 years > 45 years Stage I Any T, N & M0 pT1, N0, M0 Stage II Any T, N & M1 pT2, N0, M0 pT3, N0, M0 Stage III pT4, N0, M0 Any pT, N1, M0 Stage IV Any pT, N, M1 Undifferentiated or anaplastic carcinomas are ALL stage IV
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10 year mortalityrate for DTC Stage 10 yr mortality (%) I 1.7 II 15.8 III 30 IV 60.9
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Pre-op Surgery shouldbe within 31/7 of decision to treat Assess vocal cord function Pre-op cross-sectional CT / MRI if bulky disease or vocal cord paralysis U/S ? To plan surgery
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Surgical Terms LobectomyComplete removal of one lobe inc isthmus Near-total lobectomy Total lobectomy leaving behind a very small amount of thyroid tissue (<1 g) to protect the recurrent laryngeal nerves Near-total thyroidectomy Lobectomy with a near-total lobectomy on the contralateral side OR a bilateral near-total procedure Total thyroidectomy Removal of both thyroid lobes, isthmus and pyramidal lobe The descriptive term ‘subtotal’ no longer used
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Risks of surgeryPermanent damage to recurrent laryngeal nerve < 5 % It may not be possible to remove entire tumour without damaging both recurrent laryngeal nerves In these instances, small residue of tumour may be left behind to protect the nerves and treated with: post-op 131 I ablation TSH suppression with levothyroxine External beam radiotherapy Attempt to preserve the external branch of the superior laryngeal nerves by ligation of sup’r thyroid vessels at the capsule of gland Parathyroids – Identify & preserved where possible
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Papillary carcinoma surgeryNode –ve, <1 cm -> lobectomy > 1 cm -> Total thyroidectomy Any evidence of spread -> Total thyroidectomy Familial disease -> Total thyroidectomy Neck irrad’n in childhood -> Total thyroidectomy
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Follicular carcinoma surgeryFNAC cannot distinguish carcinoma from follicular adenoma or benign hyperplastic nodules Thy 3 mandates at least lobectomy in most cases 1 cm, minimal capsular invasion -> lobectomy Vascular invasion -> Total thyroidectomy > 4 cm -> Near-total / Total thyroidectomy ♀ , < 45 yrs, < 2 cm (Low risk) -> consider lobectomy only 2-4 cm, minimal capsular invasion -> discretion of MDT If diagnosis of cancer on lobectomy histology -> Contralateral lobectomy within 8/52
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Anaplastic thyroid CaVery poor prognosis Surgery rarely indicated 131 I no place External beam radioT + / - chemoT
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Lymphoma Most arehigh-grade B cell Thyroidectomy NOT indicated ChemoT followed by radioT OR radioT alone Excellent prognosis
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Lymph node surgeryLateral compartment of neck Levels I-V Submental, submandibular, deep cervical and posterior triangle nodes Central compartment of neck Pretracheal and paratracheal nodes Mediastinal nodes Superior mediastinal up to superior aspect of brachiocephalic vein Compartment 4 Nodes between brachiocephalic vein and tracheal bifurcation within anterior and posterior triangle Selective neck dissection Preservation of spinal accessory nerve, internal jugular vein, sternocleidomastoid muscle Radical neck dissection Radical neck Extended neck Modified radical neck dissection
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Early post-surgical MxT3 20 mg tds After total / near-total thyroidectomy Stop 2/52 before radioiodine scan or 131 I ablation Check serum calcium Check baseline post-op serum Tg at least 6/52 after surgery
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Post-op 131I ablation? Consider if Tumour > 1-1.5 cm extension beyond the capsule Unfavourable histology Decision requires MDT input Not just tumour size but also age, mets, invasion, completeness of excision, comorbidities Benefits Destruction of residual disease post-op Prolonged survival Increased sensitivity of Tg measurements
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Side effects ofpost-op 131 I ablation Early Transient hypothyroidism Abnormality of taste Nausea Neck discomfort & swelling Radiation cystitis Radiation gastritis Oedema Bleeding into secondary deposits Late Dry mouth, abnormal taste Sialadenitis & lachrymal gland dysfunction Increased lifetime incidence of leukaemia & secondary cancers Radiation fibrosis Increased risk of miscarriage Infertility in men
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Radioiodine ablation TheCountdown.... Months beforehand.... Stop amiodarone 8/52.... Stop breastfeeding 4/52.... Stop T4 2/52.... Stop T3 Low iodine diet Exclude pregnancy Consider pre-treatment sperm banking If patient likely to have more than two high dose 131 I therapies If a pre-ablation scan is felt to be absolutely necessary 99m Tc-pertechnetate scan preferable to 131 I to reduce risk of stunning Measure TSH and Tg immediately prior to Tx
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The treatment SerumTSH should be > 30 at time of ablation Consider Recombinant human TSH 0.9 mg rhTSH IM 2/7 prior to 131 I ablation 3.7 GBq (5-7.4 GBq if known mets) Discharge 3/7 after radioiodine Tx Commence thyroxine on discharge Post-ablation scan 3-10/7 later F/U clinic 2-3/12
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131 I diagnosticscans after 131 I ablation Assesses effectiveness of ablation & immediate requirement for further 131 I ablation Low risk cases may be assessed adequately by serum Tg without scan Serum TSH and Tg on day of scan TSH > 30 is required for optimal imaging
Is a repeat 131 I diagnostic scan ever required? YES in high risk disease & cases with Tg Abs interfering with serum Tg measurements YES if suspicion of disease recurrence Otherwise NO Requires thyroid hormone withdrawal prior to scan If possible, switch to T3 prior to scan as can be stopped as close as two weeks prior to scan rhTSH if thyroid hormone withdrawal contraindicated (eg IHD, panhypopituitarism) Low iodine diet 2/52 prior to scan Restart T4 3/7 after radioiodine scan No conception for 6/12 in ♀, 4/12 in ♂ post-scan
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External beam radiotherapyInfrequently indicated Adjuvant radiotherapy Gross evidence of local tumour invasion at surgery esp if residual tissue does not concentrate radioiodine Extensive pT4 disease & > 60 yrs, with extensive extranodal spread High dose external beam Unresectable tumours (esp if do not concentrate radioiodine)
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Post-Tx F/U Voicedysfunction? -> direct / indirect laryngoscopy Monitor calcium 30 % need calcium supplementation By 3/12, < 10 % require calcium supplements Calcium withdrawal should be undertaken when euthyroid Suppression of serum thyrotrophin Levothyroxine to maintain TSH < 0.1 Average dose is 175 mcg to 200 mcg Measurement of serum thyroglobulin
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Thyroglobulin Secreted bycancerous AND normal thyroid cells Therefore limited use in patients who have not had a total thyroidectomy & 131 I ablation Detection is highly suggestive of thyroid remnant, residual or recurrent tumour Endogenous TgAb may interfere with measurement TgAb valuable in interpreting Tg result Release is TSH dependent Determine TSH concurrently
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Tg measurement Moresensitive than imaging when screening for tumour recurrence NOT to be collected sooner than 6/52 post thyroidectomy or post 131 I ablation Annual check recommended Diagnostic sensitivity is enhanced by an elevated serum TSH (>30) Achieve by either thyroid hormone withdrawal (recommended) OR rhTSH stimulation IF thyroid hormone withdrawal cannot be achieved (2 x IM 0.9 mg, then measure Tg on day 5) If Tg persistently detectable or rises, further evaluation & MDT discussion required
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Long-term follow-up Lifelongbecause: Disease has a long natural Hx Late recurrences can occur which are readily amenable to Tx TFT monitoring on thyroid hormone replacement and its possible complications (hyper / hypothyroidism, pAF) Late possible s/e of 131 I Tx (eg leukaemia)