thyroid carcinoma Flashcards
thyroid carcinoma
-Primary- MC malignant tumor of the thyroid gland
-MC occurring endocrine neoplasm
-3 main histological types
-With different prognoses and clinical courses
-1. Differentiated (papillary, follicular, mixed, or Hürthle),
-2. Medullary -arise from parafollicular cells
-3. Anaplastic - arise from any cell and eventually mutates into anaplastic
-Prognosis depends on age, size, type of primary tumor, and spread
-Specialist referral
genetics
-approx 3% papillary thyroid carcinoma cases are familial -> genetic
-a lot of tx targets genetics
-Families with !adenomatous polyposis! (including Gardner’s syndrome) show increased incidence of !papillary carcinoma!
-Up to 20% of Medullary thyroid carcinoma cases may be familial
-Gardner syndrome isa form offamilial adenomatous polyposis(FAP) that is characterized by multiple colorectal polyps and various types of tumors , both benign (noncancerous) and malignant (cancerous). People affected by Gardner syndrome have a high risk of developing colorectal cancer at an early age
thyroid carcinoma
-Common presentation - hard, irregular, painless nodule
-if there is pain -> usually compression
-Fixation of nodule to local structures if the carcinoma is advanced
-Local lymph node invasion may be evident on ultrasound
risk factors for carcinoma with nodule
-History of head and neck irradiation -> especially for papillary types!
-Age <15 or > 45 years
-Increased nodule size (>4 cm) (over 1 you are concerned)
-New or enlarging neck mass
-Male gender -> nodules are MC in females….if found in male the chance of malignancy is higher
-Family history of thyroid cancer or MEN 2
-Vocal cord paralysis, hoarse voice, dysphagia
-Nodule fixed to adjacent structures
-Suspected lymph node involvement
-Iodine deficiency (follicular cancer)
papillary thyroid cancer
-Most common form!!!
-Includes mixed papillary-follicular thyroid cancer
-75-80% of thyroid cancers
-Arises from thyroid follicular cells
-Overall survival rate of 93% at 10 years
-Good prognostic features:
-Female patient
-Tumor size 4cm or less
-No local invasion or distant metastasis
-Bilateral cervical lymph node involvement indicates worse prognosis (common for this to happen)
follicular thyroid cancer
-10% of thyroid cancers
-Arises from thyroid follicular cells
-Classified as:
-Minimally invasive (excellent prognosis)
-Invasive (poorer outlook)
-Invades blood vessels with mainly -hematogenous spread -> you can find it in other parts of body
-Lymph node metastases extremely rare
-Overall survival rate of 85% at 10 years
Hurthle Cell cancer
-3% of thyroid cancers
-Arises from thyroid follicular cells
-multifocal
-Considered to be follicular cancer variant, but several important differences
-Often multifocal, bilateral, and usually nonfunctional on radioiodine scanning
-25% metastasize to cervical nodes
-Usually makes Thyroglobulin
-Hürthle cell variant of follicular carcinoma is considered higher risk
medullary thyroid cancer
-5% of thyroid cancers
-*Arises from parafollicular C-cells (produce calcitonin)
-Neck masses often painful!, sometimes B/L, often involving cervical nodes
-Up to 20% may be inherited as isolated tumor
-Or part of a syndrome involving other endocrine tumors:
-Multiple endocrine neoplasia type 2 (MEN2)- check for the other ones too
-Familial medullary thyroid carcinoma
-Baseline calcitonin - elevated
-Can be monitored postoperatively with calcitonin and/or carcinoembryonic antigen
-10-year survival rate of 75%
anaplastic thyroid cancer
-Rarest form of thyroid cancer (2-5%)
-non-differentiated, no relation, mutated
-Believed to develop from an existing papillary or follicular cancer
-Rapid, often painful, enlarging neck mass with warm discolored overlying skin
-1/3 of pts have neck pain
-Compressive symptoms (hoarseness, dyspnea, cough, and dysphagia) - common
-Do not accumulate iodine
-Highly aggressive and lethal tumor
-Median survival is <6 months; 5-year survival rate of 5%
-50% of patients have a history of palpable thyroid nodule and differentiated cancer is found in 80% of cases (thought to stem from the others)
-More common in areas with endemic goiter (thought to stem from it -> mutation)
signs and symptoms
-Usually painless nodule- Although occasionally some pain or tenderness
-Often asymptomatic
-Slow or rapid growth may have been noticed
-May have compressive symptoms:
-Hoarseness
-Dysphagia
-Dyspnea
-Solitary thyroid mass
-Or dominant nodule in multinodular goiter (more likely differentiated cancer)
-Usually a hard, painless mass
-May be fixated to adjacent structures
-Enlarged cervical lymph nodes ±
-Rapidly growing neck mass ±
-Signs of invasion of surrounding structures:
-Stridor
-Hoarseness
papillary vs follicular vs medullary vs undifferentiated
differential dx
-Benign solitary thyroid nodule- cystic
-Thyroglossal cyst- MC congenital anomaly of the central portion of the neck
-Primary thyroid lymphoma
-Metastatic spread to thyroid- Lung, breast, melanoma
-Squamous cell carcinoma of the thyroid
-Very rare primary variant
-Frequently associated with clinical syndrome of hypercalcemia and leukocytosis
-can be cyst OR nodule (hyper/hypothyroid)
evaluation
-Maintain a high index of suspicion about all thyroid nodules until definitively proven to be benign
-Diagnosis is suspected on the basis of the clinical findings
-Confirmed by histology
-Fine-needle aspiration is the procedure of choice in the evaluation of thyroid nodules
suspicious nodule flow chart
- do US before bx
initial work up of thyroid nodule
-FNA - about a 5% false-positive and 5% false-negative rate in !papillary cancer!
-About 15-25% of follicular adenomas are malignant -> Needle bx cannot distinguish between malignant and benign forms
-All pts with medullary thyroid cancer should be screened for pheochromocytoma
-TSH and Thyrotropin test— followed by a thyroid US *
-The following pts should have FNA and/or excisional biopsy:
-All pts with thyroid nodules >1.0cm
-Or with suspicious ultrasound features (firm, fixed, solitary, evidence of lymphadenopathy, invasion or compression of adjacent structures)
-Or with a positive family history of thyroid cancer
-And/or a personal history of head/neck irradiation
tests
-TSH
-US- confirm location
-FNA
-radioiodine imaging
-serum calcitonin
-serum thyroglobulin
tests: TSH
-Usually normal in thyroid cancer; 0.35-5.5mcU/mL )
-Hyperfunctioning (which are rarely malignant) vs. nonfunctioning nodules
-If TSH suppressed - radioiodine imaging rather than FNA
tests: US exam
-confirms location
-Cystic vs. solid nodules
-Guides FNA
-Very sensitive
-Nodules >1.0cm in diameter or smaller nodules with concerning characteristics – refer for FNA & biopsy
tests: FNA
-Can be done in office setting
-Cytology is diagnostic in 80-90% of cases
-3 aspirations are recommended
tests: radioiodine imaging
-Not diagnostic of malignancy
-just tell you if hyper or hypo functioning
-Has no role in diagnosis of thyroid cancer
-May help to distinguish a hyperfunctioning vs. nonfunctioning nodule
-radionuclide scanning:
-Hot nodule
-Abnormally high uptake = hyperfunctioning nodule; blacker on scan
-Minimal risk of malignancy
-Cold nodule
-Low uptake = nonfunctioning nodule; paler on scan
-Increased risk of malignancy
-Useful for postoperative dx of recurrence or metastasis, especially after total thyroid ablation
tests: serum calcitonin
-Useful if family history of medullary thyroid cancer or MEN2
-To confirm diagnosis of medullary carcinoma following aspiration cytology
serum thyroglobulin
-Rarely helpful in initial dx
-Very high with a small nodule - ???metastatic thyroid cancer
-Useful for post-treatment screening for recurrence!!!!!
goal of treatment
-Surgical removal of the malignant tumor
-large resection for lymph node/fibrosis
-Treatment of local and distant spread
-Provision of long-term follow-up and surveillance to ensure early detection of recurrences
-Palliative tx for pts with untreatable anaplastic tumors
-Screening of family members in the case of medullary carcinoma -> high risk for family
treatment
-All well-differentiated thyroid cancers - surgically excised
-Surgery allows accurate histological dx and staging
-Multicentric disease commonly found in contralateral lobe
-Lymph node spread - also assessed & involved nodes removed
-Extent of surgery varies
-Survival rates are similar for lobectomy and near-total thyroidectomy
-Lobectomy -associated with a lower incidence of hypoparathyroidism and injury to the recurrent laryngeal nerves
anaplastic tumors treatment
-Neck CT scan and chest X-ray should be performed at the time of dx!!!!!!!!!!!!
-If locally resectable -> thyroidectomy plus selective resection of involved local or regional structures and lymph nodes
-depends on expected survival rate
-If unresectable -> Airway management with or without tracheostomy and pain control are critical
-Main objective is control of symptoms, particularly pain and airway obstruction !!!!
thyroidectomy
-Total thyroidectomy - procedure of choice for most pts -> Involves the removal of all visible thyroid tissue
-Subtotal thyroidectomy -> Removal of all grossly visible tissue leaving a small amount (<1g) adjacent to the recurrent laryngeal nerve
-Thyroid hormone replacement therapy for lifetime
total thyroidectomy
-Indications
-Patients aged <15 or >45 years, with a lesion >1.5cm
-All cases of papillary thyroid cancer
-Follicular carcinoma with any degree of invasion
-Hürthle cell carcinoma
-Medullary thyroid cancer
-Contraindications
-Lymphoma !
-Unresectable anaplastic thyroid cancer
-Occult papillary thyroid cancer
-Small follicular lesions without invasion
modified radical neck dissection
-Designed to remove all lymph node tissue in the lateral neck, from the clavicle to the angle of the jaw, without sacrificing the muscles, internal jugular vein, or nerves !!!
-Extends normal thyroidectomy incision laterally
-Papillary thyroid cancer
pharmacotherapy
-Levothyroxine
-Replacement therapy after total thyroidectomy
-Suppress thyrotropin production, therefore depressing growth in differentiated tumors
-Lithium
-Pretreatment may be used as an adjunct to radioactive iodine to enhance the half-life of 131-iodine and increase its therapeutic impact
radioiodine ablation
-Performed 4-6 weeks after surgery to ablate remnant thyroid tissue and distant metastases
-Post-treatment scan is performed 7 days after 131-iodine
-Most useful for patients with locally invasive disease, metastatic spread, or inoperable cervical lymph node metastases
-Low-iodine diet for 2 weeks prior to 131-iodine
-surgery is first option
chemotherapy
-Used occasionally for !differentiated thyroid! cancers that have not responded to traditional therapy
-Doxorubicin - most active single agent
-Often used in combination with external radiation in anaplastic carcinoma
external beam therapy
-Routine treatment in*:
-Anaplastic thyroid carcinoma
-Primary thyroid lymphoma
-Little or no role for radiotherapy if cancer is resectable
-May also be beneficial for:
-Treatment of localized bony metastases
-Poorly differentiated tumors that do not concentrate radioactive iodine
-Also used to treat bone pain due to metastases
prognosis
-The best prognoses- Young people with localized tumors <2cm (children <10 years and older adults have a worse prognosis)
-Overall 10-year survival for papillary carcinoma is 95%; follicular 90%; medullary 70-75%
-Involvement of cervical nodes is predictive of recurrence in older patients (>45 years), but not overall survival
-Even when !differentiated tumors! present initially with distant metastases, long-term survival is 43%
-Prognosis is poor for anaplastic tumors; 5-year survival is rare
-Overall survival in thyroid cancer patients is excellent
clinical pearls
-The best serum marker for monitoring papillary and follicular carcinomas -> Thyroglobulin
-The best serum marker for medullary carcinoma is calcitonin !!!!
-Disease progression:
-Often first manifests as a rising thyroglobulin
-If whole-body radioiodine scans confirm the presence of recurrent or worsening disease, 131-iodine ablation repeated
-Postoperative surveillance!!! - neck ultrasound and thyroglobulin levels
-With total thyroidectomy, the thyroglobulin level should be undetectable, so any rise in thyroglobulin suggests a recurrence
-The presence of remaining thyroid tissue makes these levels difficult to interpret
