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Carcinoma of Thyroid. Prof. S. Deivanayagam MS Professor & HOD of Surgery Madras Medical College. Ca. Thyroid - Types : -. Primary / secondary Follicular cell-derived Papillary thyroid cancer Follicular thyroid cancer Anaplastic thyroid cancer Lymphocyte derived
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Carcinoma of Thyroid Prof. S. Deivanayagam MS Professor & HOD of Surgery Madras Medical College
Ca. Thyroid - Types : - • Primary / secondary • Follicular cell-derived • Papillary thyroid cancer • Follicular thyroid cancer • Anaplastic thyroid cancer • Lymphocyte derived • Lymphoma • C-Cell derived • Medullary thyroid cancer • Secondary – breast, colon, melanoma
Differentiated Thyroid Ca. : - • 85% of all thyroid cancers • Derived from follicular cells • Types • Papillary carcinoma • Follicular carcinoma • Mixed Papillary – Follicular • Hurthle cell carcinoma
Etiology & Risk factors : - • Male sex • Previous neck irradiation • For Hodgkin’s lymphoma – Papillary ca. • Pre-existing lesions • MNG – Follicular ca. • Hashimoto’s – Papillary ca. (controversial) • Iodine deficiency – Follicular ca • Family H/O • Familial Syndromes
Clinical Features : - • MC presentation – Painless swelling in the neck • Pain • Dysphagia • Stridor • Rapid enlargement • Hoarseness of voice (most important) • Dyspnoea, Hemoptysis (late & rare) • Lateral aberrant thyroid – lymphnodemets in papillary ca. thyroid • Pulsatile bony secondaries in follicular thyroid ca.
Papillary Thyroid Ca. : - • Most common type (~80%) • Young females (mean age 30 - 40 yrs) • Least malignant – one of the curable malignancies • Commonly metastasize to neck nodes • Distant metastasis uncommon • Minimal or occult/microcarcinoma refers to tumours of 1 cm or less in size with no evidence of local invasiveness through the thyroid capsule or angioinvasion, and that are not associated with lymph node metastases
PTC – Types : - • Types • Follicular variant • Tall cell • Columnar cell • Diffuse sclerosing Poor Prognosis • Insular • Breaking of capsule
PTC – Pathology : - • Gross : - • Multi-focal • Unencapsulated but often has pseudocapsule • Microscopic : - • Closely packed Papillae • Psammoma bodies • Oval or elongated pale staining nuclei with ground glass appearance– Orphan Annie eye cells
Investigations : - • USG neck • To identify the lesion • To categorize the nodule • To detect associated lymphadenopathy • To take guided FNAC • FNAC • Best first line diagnostic procedure for papillary ca. • Thyroid function test
PTC – Prognostic Systems : - • AGES – Age, Grade, Extent & Size • AMES – Age, Mets, Extent & Size • GAMES – Grade, Age, Mets, Extent & Size
PTC – Prognostic Systems : - • DeGroot’s classification • Class I – Intra-thyroidal • Cass II – Cervical node mets • Class III – Extra-thyroidal invasion • Class IV – Distant mets • Most important prognostic factor – Age at diagnosis • Lymph node mets – No prognostic significance
Follicular Thyroid Ca. : - • Accounts for ~10% of thyroid ca. • Common in females • Mean age 40 – 50 yrs • Common in iodine deficient areas • May coexist with MNG • Metastasize to flat bones – pulsatile bony secondaries • Lymph node metastasis uncommon
FTC – Types : - • Minimally invasive • Capsular invasion without involvement of surrounding parenchyma and vascular invasion (except those within tumour) • Widely invasive • Surrounding parenchymal and / or vascular invasion
FTC – Pathology : - • Gross • Solitary & Encapsulated • Microscopic • Well differentiated cells • Presence of Vascular and / or capsular invasion • FNAC & frozen section cannot distinguish between follicular adenoma & carcinoma • Minimal tissue required - Hemithyroidectomy
TNM Classification : - • Common for all differentiated thyroid carcinomas • The only TNM system to incorporate the age of the patient • Separate for differentiated, medullary and anaplastic ca.
DTC - Treatment : - • Surgery remains the main stay of treatment for DTC • Types of Surgeries : - • Total thyroidectomy – Removal of all thyroid tissue with preservation of parathyroids • Total thyroidectomy remains Gold standard
Total thyroidectomy – Rationale : - • Total thyroidectomy – Pros : - • Enables usage of RAI effectively • Makes serum Tg a sensitive marker for recurrence • Enables better removal of central compartment nodes • Reduces the risk of recurrence • Reduces the risk of re-operation • Total thyroidectomy – Cons : - • Risk of RLN injury & hypocalcemia
Node management in DTC : - • Without lateral group enlargement – Total thyroidectomy with central compartment node dissection • With unilateral lateral group nodes mets – Total thyroidectomy with MRND • With b/l lateral group nodes mets – Total thyroidectomy with b/l MRND • Prophylactic neck dissection – NOT indicated
Post-op 131I adjuvant therapy : - • Specific uptake into follicular cells • Emits both βparticles andγ rays • γ rays are therapeutic while βparticles produce radiation toxicity • Indications : - • Positive radio-iodine uptake scan post total thyroidectomy
131I ablation continued… • Precautions : - • Stop thyroxine for 4-6 wks • TSH > 30-50 mU/L for maximal effect • Avoid iodinated contrast CTs, salts & pain balms • Therapeutic dose : - • Low risk pt. – 30-100mCi • High risk pt. – 100-200mCi
Role of Chemo & Radiotherapy : - • Radiotherapy - Indications : - • Unresectable disease • Metastasis in support bones to avoid fractures • Painful metastasis • No role for routine chemotherapy • Doxorubicin is commonly used mainly as a radiation sensitizer
Post-op follow up : - • Suppressive dose of thyroxine – till TSH <0.1mU/l • RAI Scanning : - • 6-12mth after initial ablation • If consecutively negative - >95% 10yr relapse free survival • Subsequent scans – only if clinically indicated • Thyroglobulin : - • Level >2ng/ml – suggestive of recurrence / mets • Tg & anti-Tg antibodies level should be measured every 6mth in first year, and then annually
Hurthle Cell Ca. : - • Variant of Follicular cell ca. • Women > Men • Affects older age group ~65 yrs • Defn. - An encapsulated group of follicular cells with at least a 75% Hurthle cell or Oncocyte component • “Large, polygonal, eosinophilic thyroid follicular cells with abundant granular cytoplasm and numerous mitochondria” - Askanazy
Hurthle Cell Ca. continued..: - • Often multicentric • Diagnosis requires demonstration of capsular and / or vascular invasion • Regional lymph nodes involved ~30% & is a poor prognostic indicator • Distant metastasis in ~15% • More aggressive & poorer prognosis
Hurthle cell ca. – Treatment : - • Total thyroidectomy & central compartment node dissection recommended • MRND done in case of enlarged lateral nodes • Post op management : - • Thyroid suppression • Serum thyroglobulin measurement every 6 months • Postoperative radioactive iodine is usually not effective (10% concentrate iodine)
Medullary Carcinoma : - • Arises from Para-follicular C cells from neural crest • Constitutes 3 –10 % of all thyroid cancers • Types • Sporadic • Hereditary (Familial or MEN II)
Clinical features: - • Symptoms due to the tumour • Both lymphatic & hematogenous spread common • Paraneoplastic Syndromes • Due to secretion of calcitonin, VIP, serotonin and somatostatin • Diarrhoea – most common
Medullary Ca. - Peculiarities : - • Characteristic amyloidstroma on HPE • Doesn’t take up radioactive iodine • Both I-131 scan and radio-iodine ablation are of no use • Serum calcitonin elevation – tumour marker • Presence of lymph node metastasis is a poor prognostic indicator
Investigations : - • FNAC • USG / CT neck • Calcitonin confirms the diagnosis • CEA (>50% of tumours) • USG abdomen & 24hr urine catecholamines – to rule out pheochromocytoma
Treatment : - • Without neck nodes – Total thyroidectomy with central compartment neck dissection • With neck nodes – Total thyroidectomy with MRND of the involved side • External beam RT • Extra-thyroidal extension(T4 disease) • Unresectable / metastatic disease as palliation • Follow up – serum calcitonin & CEA monitoring
Anaplastic Carcinoma : - • Most aggressive and fortunately rarest variety • Invariably well advanced at presentation • Worst prognosis • Treatment – Palliative External beam RT • Surgery – isthumusectomy to relieve tracheal obstruction
Carry Home Message : - • DTC carries very good prognosis and when detected early is a curable disease • Total thyroidectomy with central node dissection is the gold standard treatment in both DTC & MTC • MRND is optional • RAI ablation plays a key role in metastatic disease in DTC