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Endocrine 2 > Thyroid Cancer > Flashcards

Thyroid Cancer Flashcards

1
Q

List 4 types of thyroid cancer and frequency of occurrence

A 
- Follicular cell origin
• Papillary (80%)
• Follicular (15%)
• Anaplastic (very rare)
- C-cell (parafollicular cell) origin (5%)
• Medullary carcinoma
- Primary thyroid lymphoma (rare)
- Primary thyroid sarcoma (rare)
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2
Q

How does age and sex relate to risk of malignancy ?

A
  • Solitary nodules likely be malignant >60 yo and <30 yo

- higher risk in males

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3
Q

What is the typical presentation of a thyroid carcinoma

A
  • Asymptomatic, palpable, solitary thyroid nodule
  • Not painful or tender
  • No hyper- or hypothyroidism
  • Dx: FNA bx
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4
Q

Identify the signs and symptoms associated with thyroid malignancy

A
  • Nodular growth
  • Rapid growth: ominous sign
  • Hard and fixed nodule
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5
Q

Describe the common findings on physical examination of a patient with thyroid cancer

A
  • Should include thorough head and neck exam, careful attention to thyroid gland and cervical soft tissue, indirect laryngoscopy
  • Solitary nodules can range from soft to hard
  • Hard and fixed: more suggestive of malignancy than supple and mobile
  • Firm cervical masses are highly suggestive of regional lymph node metastases
  • Vocal cord paralysis implies involvement of recurrent laryngeal nerve
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6
Q

What is the goal of a solitary thyroid nodule workup?

A

differentiate malignant from benign - determine who needs intervention vs. who needs serial monitoring

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7
Q

What are the components of a solitary thyroid nodule workup?

A
  • History
  • PE
  • lab eval
  • FNAB
  • Imaging can be adjunct in select cases
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8
Q

What is the most important diagnostic tool in a solitary thyroid nodule workup?

A

FNAB

is the first intervention and determines the next step in nodule management

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9
Q

4 Possible results of FNAB

A
  • Benign disease
  • Malignant disease
  • Indeterminate for diagnosis
  • Non-diagnostic
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10
Q

What often occurs with repeated biopsies?

A

Up to 50% of repeated biopsies result in definitive dx

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11
Q

What often occurs with indeterminate or non-diagnostic results

A

despite repeat biopsy, can undergo lobectomy sx for tissue dx

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12
Q

What is f/u for non diagnostic results?

A

can be monitored clinically, and radioiodine scans can be useful for determining the functional status of the nodule (most hyperfunctioning nodules are benign)

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13
Q

What is action for malignant results?

A
  • require surgical intervention
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14
Q

what type cancers are often positively IDed on FNAB alone?

A

Papillary thyroid carcinoma and MTC

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15
Q

what two cancers are very difficult to distinguish on FNAB alone? what should be done?

A
  • follicular adenoma from follicular carcinoma
  • Should undergo sx for thyroid lobectomy for tissue dx
  • Require complete thyroidectomy if malignancy is discovered on review of pathology
  • Some controversy regarding extent of thyroidectomy for particular pathologic diagnosis…
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16
Q

What is the role of serum TSH in the w/u of a thyroid nodule?

A
  • Low suggests autonomously functioning nodule, typically benign
  • Malignant dz cannot be ruled out on basis of low or high TSH levels
17
Q

What is the role of serum calcitonin in the w/u of a thyroid nodule?

A

Elevated: highly suggestive of medullary thyroid carcinoma

18
Q

What are the three imaging studies used to dx thyroid cancer?

A
  1. Neck US
  2. Thyroid radioiodine imaging
  3. Neck CT/MRI
19
Q

What is the role of Neck US in dx of thyroid cancer?

A
  • MC modality to eval thyroid dz
  • Limited usefulness for distinguish btwn malignant and benign nodules
  • Per American Thyroid Association, is most important imaging modality in eval of thyroid cancer. Should be used routinely to assess primary tumor and all associated cervical lymph node basins preoperatively
20
Q

What is the role of thyroid radio iodine imaging in the dx of thyroid cancer?

A

Determine functional status of a nodule but cannot exclude carcinoma

21
Q

What is the role of neck CT/MRI in the dx of thyroid cancer?

A
  • Avoid iodinated contrast agents
  • Eval soft-tissue extension of large or suspicious thyroid masses into neck, trachea, esophagus. To assess metastases to cervical lymph nodes
  • No role in routine management of solitary thyroid nodules
22
Q

Describe the risk factors for thyroid papillary carcinoma

A
  • MC thyroid malignancy
  • F>M
  • Mean age 34-40
23
Q

List the metastatic sites for thyroid papillary carcinoma

A
  • Has a propensity to spread to cervical lymph nodes (1/3 of pts at presentation of cancer have clinically evident lymph node metastases)
  • 5-10% develop distant metastases, MC lungs and bone
24
Q

Outline the treatment of thyroid papillary carcinoma

A
  • Total thyroidectomy (GS)
    • Lobectomy also an option if <4 cm, pro is reduced risk of complications
  • +/- Radioactive iodine if TSH is elevated
    • Thyroid remnant ablation/treatment
  • Levothyroxine at a dose that suppresses plasma TSH to below normal range – inhibits growth of residual tumor cells
  • Lifelong monitoring with plasma thyroglobulin and neck US
25
Q

What structures are at risk in a patient undergoing a total thyroidectomy

A
  • Recurrent laryngeal nerve
  • Superior laryngeal nerve
  • Parathyroid glands
26
Q

What is the treatment of thyroid papillary microcarcinoma

A
  • Total thyroidectomy or lobectomy if contralateral lobe is nl
  • RAI if TSH is elevated
    • Thyroid remnant ablation/tx is NOT required for unifocal or multifocal papillary microcarcinoma
  • TSH suppression therapy not required. Goal TSH: 0.5 to 2.0 mIU/mL
  • F/U: yearly non-stimulated thyroglobulin, every few years neck US
  • Active surveillance: growing interest. Japanese studies show in all cases was very effective over 5 to 10 years
27
Q

Describe 8 characteristics of follicular thyroid carcinomas

A
  • 2nd MC thyroid malignancy
  • Greater proportion of thyroid cancers in regions where dietary intake of iodine is low
  • F>M 3:1
  • Usually older onset than papillary carcinoma (4th to 6th decade)
  • Arise from follicular cells
  • Neoplastic cells are TSH sensitive, take up iodine and produce thyroglobulin
  • More aggressive than papillary thyroid carcinoma
  • Metastasize early to lung and bone (but not usually cervical lymph nodes)
28
Q

What is the tx of follicular thyroid carcinomas

A

same as papillary thyroid

29
Q

Why is radioactive iodine (RAI) used to treat thyroid cancer

A
  • Concentrates in thyroid cells
  • Radiation can destroy the thyroid gland and any other thyroid cells (including cancer cells) that take up the iodine
  • Little effect on the rest of the body
  • Radiation dose is much stronger than dose used in radioiodine scans
  • Can be used to ablate any thyroid tissue not removed by sx or to treat some types of thyroid cancer that have spread to lymph nodes and other parts of the body
30
Q

What two types of cancer is RAI used in

A

papillary or follicular thyroid cancer

31
Q

What is required for RAI to be effective?

A
  • pt must have high levels of TSH in the blood which stimulates thyroid tissue to take up the RAI
  • Can induce via thyroid hormone withdrawal – intentional temporary hypothyroidism followed by injectable form of thyrotropin for two days, then RAI on day three
32
Q

what diet is recommended prior to RAI treatment

A

a low iodine diet for 1-2 weeks before tx (avoid iodized salt, dairy, eggs, seafood, and soy)

33
Q

What is the indication for radioactive iodine in the treatment of thyroid cancer

A
  • TSH is elevated

- Follicular or papillary thyroid cancer

34
Q

why is thyroglobulin used to monitor patients with thyroid cancers

A
  • Protein produced by follicular cells of thyroid
  • Used entirely in the thyroid gland
  • Precursor of thyroid hormones: thyroglobulin’s tyrosine residues are combined with iodine
  • Used as a marker for persisting disease and recurrence after thyroidectomy
35
Q

• Identify the clinical data that changes the risk assessment of a patient with thyroid cancers

A
  • Age at dx is one of the most important prognostic features
    • >40 is higher risk of cancer-related death
    • Recurrence more common when dz dx <20 and >60
  • Sex
    • Men 2x as likely to die from thyroid cancer
  • Size
    • >4 cm have increased risk of recurrence and cancer-related mortality rates
  • Histology
    • Papillary carcinoma is associated with 30-year cancer-related death rate of 6%
    • Follicular carcinoma is associated with 30-year cancer-related death rate of 15%
  • Invasion of surrounding tissues outside thyroid indicates biologic aggressiveness, significantly worsens prognosis
  • Lymph node metastasis: not as important in outcome of well-differentiated thyroid carcinomas as in other solid tumors
  • Distant metastases: If found on initial exam, associated with 68.1-fold increase in rate of disease-specific death
  • Socioeconomic factors: affect survival, lower household income associated with higher disease-related death
36
Q

What are the sources of medullary thyroid cancer (MTC)

A

75% sporadic
- More commonly not multifocal

25% familial

  • More commonly multifocal
  • Component of MEN2A and MEN2B and familial MTC syndrome (All caused by mutations of different regions of the RET proto-oncogene)
37
Q

What labs are used to monitor for MTC

A
  1. plasma calcitonin - elevated

2. CEA - elevated

38
Q

Outline the treatment for MTC

A
  • Total thyroidectomy and lymphatic dissection of anterior compartment of the neck
  • If vasculature of parathyroid gland is disrupted, autotransplantation of parathyroid gland into SCM muscle or non-dominant forearm is performed.
  • Might perform prophylactic thyroidectomy/central-compartment lymph-node dissection in children with MEN2A, 2B
  • Monitor for recurrence with plasma calcitonin and CEA (would be elevated)
  • Levothyroxine tx should be adjusted to keep plasma TSH level within nl range
  • RAI NOT useful

Endocrine 2 (15 decks)

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