Thyroid cancers

•Infrequent cancers-3% of all cancers

•Benign diseases common

•Requires multidisciplinary action

•Women are affected 3 times more than men

•Peak incidence 30-40yrs

Types-

• Papillary-80%

• Folllicular-10%

• Medullary-5-10%

• Anaplastic-1-2%

• Lymphoma

• Sarcoma

Etiology & Risk factors

• Arise from 2 types of cells• Follicular cells makes papillary,follicular &

anaplastic• Parafollicular C cells makes medullary

• Radiation exposure & Hashimotos thyroiditis are risk factors for papillary ca.

• Low dietary iodine is riskfactor for follicular & anaplastic

History• Present as Painless palpable thyroid

nodule\

• Nodules are present in 4-7% of population but most are benign,5% are mlignant

• Peak incidence occurs between age of 30-50yrs

• More common in females

• Malignant nodules are usually painless

• Hoarseness suggests malignancy-nerve involvement

• Dysphagia

• Family history present in case of medullary cancer

Examination

• Thyroid gland

• Soft tissues of neck

• Tenderness?

• Consistency(Hard/firm/soft) mobility(fixed or not)

• Laryngoscopy if hoarseness presents

GOAL is

• To differentiate malignant from benign nodules

• Determine which patient require intervention / who can be monitered

• Avoid unnecessary surgery

FNAC

• First intervention in evaluation of nodule• Inexpensive,easy,few complications• Needs a good cytopathologist• Four types of results-benign-69% mallignant-4% indeterminate-10% nondiagnostic-17%Sensitivity-83%,specificity-91%

• If nondiagnostic-repeat

• If benign-followup

• If malignant-surgery

• If indeterminate-surgery

Lab

• TSH-to know the hyper/hypo thyroidism,

not helpful in malignancy

• Sr.Thyroglobulin as a tumour marker in post op to assess

• Calcitonin for medullary ca.

Imaging

• U/S-to differenciate solid & cystic lesions,for FNA accuracy & for monitoring of benign lesions

• Scans-determine function of nodule

• Carcinoma can not be ruled out based on scans as 4%of hot nodules also malignant

• CT/MRI not used routinely

Papillary cancer

• Most common(80%)

• Women-3 tims more common

• 30-40yrs of age

• Risk factors-radiation exposure in childhood, Hashimotos thyroiditis

• Slow growing,TSH sensitive,take up iodine,TSH stimulation produces Tg response

Pathology

• Unencapsulated,arborizing papillae,well differentiated,rare mitoses50% have Psammaoma bodies-calcific concretions,circular laminations

• Multicentric

• Histology-Orphan anney eye with nuclear grooving

• Loacl invasion through capsule, invading trachea, nerve causing dyspnea, hoarseness

• Propensity to spread to the cervical lymphnodes,clinically evident in 1/3 of patients-mostly central compartment

• Distal spread to lung & bones

Follicular carcinoma

• Second most common(10%)

• Iodine deficient areas

• 3 times more in Women

• Presents more in advanced stage than papillary

• Late 40’s

• Also TSH sensitive, takes up iodine, produces Tg

pathology

• Round, encapsulated, cystic changes,fibrosis, haemorrhages

• Microscopically neoplastic follicular cells

• Differentiated by follicular adenoma by capsular invasion & angioinvasion

• Cannot reliably diagnose based on FNA

• Local invasion is similar to papillary cancer with same presentation

• Cervical metastases are uncommon

• Distant metastases is significantly higher(20%),with lung & bone as most common sites

Treatment & Prognosis

• Total thyroidectomy with lymphnode dissection if positive nodes present is mainstay of treatment for differentiated thyroid cancers

• Post surgery radioiodine scan for detection & ablation of remnant thyroid tissue in neck or in metastatic sites

Post operative radioiodine & Ablation

• I-131 targets residual thyroid tissue & tumour after thyroidectomy

• First given in diagnostic dose to detect & then in therepeutic dose to ablate it

• Hypothyroid state (TSH>30mIU/l) is required for better iodine uptake for that routine eltroxin supplimentation after surgery is to be avoided

Thyroid supression therapy

• Low TSH levels reduce the tumour growth rates & recurrence rates,so after surgery & radioablation patients should be maintained on thyroxin

• Most recommended TSH level is <0.1mIU/l

• Followup 6monthly with thyroglobulin level & scans are recommended

Prognosis

• Age at diagnosis-Cancer related deaths are more common if patient is older than 40yrs

• Recurrences are common in patients diagnosed at <20yrs / >60yrs of age

• Men are at double risk to die

• Tumors of >4cm have high recurrence rate & deaths

• 30yr cancer related death rate is 6% for papillary & 15% for follicular cancer

• Local invasion portends poorer prognosis

• LN metastases is not important for prognosis

• Distant metastases associated with 68fold increase in disease specific death rate

Hurthle cell carcinoma

• A Variant of follicular cancer,also known as oncocytic carcinoma

• 5yr survival-50%• More common in females and in 5th decade of

life• Same clinical presentation as follicular ca.• Can not be diagnosed on FNA• Does not take up Iodine, so treat aggressively• Radio iodine, Thyroid suppression does not work

Medullary carcinoma

• 5% female preponderance

• 75% sporadically,25% familial.

• In familial cases, the lesions are usually all over the gland whereas in sporadic they are not

• Associated with MEN 2a,2b & FMTC syndromes

• MEN 2a - also known as Sipple syndrome

MTC, pheochromacytoma, pitutory,parathyroid adenomas• MEN 2b – MTC, pheochromacytoma, ganglionomas/neuromas, morphanoid habitus• FMTC – only MTC• MTC in familial cases are more aggressive,

presents in younger age, with rapid growth & metastases

• Whereas in sporadic cases presents as painless nodule/symptoms of invasion

Biochemical test in MTC

• Calcitonin levels are used as tumour marker for MTC in post op to detect recurrence

• Stimulating Calcitonin release with IV pentagastrin increases sensitivity of test- first measures baseline calcitonin, then gives pentagastrin, then measure calcitonin serially at 1.5 & 5min intervals

• Genetic test to detect RET gene for screening• Histologically test for Calcitonin,CEA

Treatment for MTC

• Total thyroidectomy• Lymphnode dissection of level 6• Parathyroid reimplantation if necessary• Prophylactic thyroidectomy in children with

MEN 2a,b (>90% penetrance)• Survielance with Calcitonin, CEA• Does not take up iodine, so no radioiodine• Prognosis-10yr survival rate is 65%

Anaplastic cancer

• Bad

• Aggressive, much invasive

• Surgery is not indicated

• Radio/chemotherapy

Indications for total thyroidectomy

• Well differentiated thyroid cancer

• Medullary thyroid cancer

• Sarcoma of thyroid

• Lymphoma of thyroid

• Obstructive goitre

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