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33 terms

Thyroid Cancer

Ch 11 - Hansen
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What are the risk factors for thyroid cancer
- female (3:1 ratio)
- ionizing radiation: leads benign and malignant thyroid disease and typically low grade papillary
- chronic TSH stimluation (w low iodine diets,
- Hashimoto's thyroiditis
- Genetic syndromes
Which Genetic syndromes are ass't with thyroid cancer
Papillary
- familial adenomatous polyposis
- Gardener's syndrome
- Cowden's syndrome

Medullary
- ~20% have either MEN 2a or MEN2B
- familial medullary carcinoma
What histologies are possible
Papillary thyroid carcinoma:

Follicular thyroid carcinoma:

Hurthle Cell

Medullary thyroid cancer

Anaplastic thyroid cancer
What is the LN drainage
-initially to the central compartment
-nodes to tracheo-eosphageal grove
-nodes anterior to the larynx and above the isthmus (Delphian)
- cervical LN are freq involved
Where are the sites of distant mets
lung > bone > liver
What are the important prognostic factors
AGE - most important
other:
- large tumour size
- ETE
- higher grade
- postop macroscopic disease
- male
- distant mets
What is the typical treatment
- Surgery (total thyroidectomy, prophylactic central neck and lateral neck dissection)

- thyroid hormone suppression (keep TSH <1)

- RAI

- EBRT if high risk (multiple recurrences, positive margins, no RAI uptake, anaplastic cell type)
What is the sensitivity, specificity and accuracy with a thyroid FNA
Sens - 98%

Spec - 99%

Accuracy - 98%
What are typical presenting S+S
most common = asx palpable thyroid nodule

other:
- large mass
- hoarseness
- invasion into larynx, pharynx, esophagus
What is the role of radionuclide scintigraphy and thyroid ultrasound
As complementary tests b/c an FNA determines diagnosis well
What is the concern with CT scans prior to RT
iodinated contrast will block treatment with I-131 for up to 6 months

- determine if eligible by investigating 24 hr iodine measurement
What are the typical thyroid panel of blood tests
T3
T4
TSH
thyrglobulin
What investigations are needed for medullary thyroid carcinoma
- serum calcitonin and CEA
- calcium
- urine and serum catecholamines
- RET mutation (b/c ~20% risk of MEN)
MACIS score
Metastasis: +3
Age: 0.08 x age
Completeness of resection: +1
Invasive locally: +1
Size: 0.3 x size in cm
MACIS score outcomes
20 yr CSS:
<6: 99%
6-6.99: 89%
7-7.99: 56%
8+: 24%
Treatment recommendations for low risk papillary/follicular/hurthle cell
Total thyroidectomy. measure TSH, thyroglobulin, free T4, anti-TG antibodis at 4-6 wks
- maximal levothyroxine therapy

Typically if MACIS <6
Treatment recommendations for high risk pap/foll/hurthle
- thyroidectomy with LN dissection
- RAI scan (I-123) followed by ablation (I-131)
- If LN +can consider EBRT
treatment recommendations for medullary carcinoma
Locoregional disease
- Total thyroidectomy with central level VI LN dissection
- + EBRT if margin +, extensive LN involvement, T4a, unresectable
- Follow Calcitonin and CEA post-op

Metastatic disease:
- palliative chemo (doxorubicin + cisplatin)
treatment recommendations for anaplastic thyroid cancer
- GTR only chance of cure
- EBRT (evidence of altered fractionation; I have seen 60 in 25 in past)
- consider RAI after above
Preparation for RAI
- low iodine diet x 2-3 wks
- switch to cytomel 6 wks pre RAI and then stop cytomel 3 wks pre RAI
(OR consider artificial TSH stimulation with thyrogen (recombinent TSH))
- Iodine scan with I-123 (b/c gamma emitter) to determine uptake in thyroid bed/tumour etc. to determine safe dose of I-131 to give
- Treat with 100-200 mCi I-131
- need to isolate x 3 days (if hospitalized can be discharged once below 30 mCi emission)
- ~5 days later repeat scan to see uptake of I-131
- can repeat 4-6 months later if second scan positive
Side effects of RAI
acute;
- sialadenitis
- fatigue
- xerostomia
- cystitis
- gastritis
- diarrhea
- pain
- transient leukopenia/thrombocytopenia
- oligospermia in males (avoid pregnancy x6 mo)

Chronic:
- increased risk of leukemia if >800 mCi total
- increased risk of breast and bladder cancer if >1000 mCi
- late pulmonary fibrosis (if sig pulm mets)
- await 6 months before attempting pregnancy
characteristics of papillary thryoid ca
- arise from follicular cells
- takes up RAI
characteristics of follicular thryoid ca
- cannot diagnose on FNA b/c cells are same as benign follicular adenoma except they are invasive
- takes up RAI
characteristics of Hurthle cell ca
- more aggressive than pap or follicular carcinomas
- 10 yr OS 76% (vs 85% for other two)
- takes up RAI
- ass't with Hashimoto's thyroiditis
characterisitics of medullary thyroid carcinoma
- arises from the parafollicular/C cells that produce calcitonin
- monitor disease using calcitonin levels
- does NOT take up RAI - but may use for primary disease b/c of cross fire from residual normal thyroid cells
characteristics of anaplastic thyroid cancer
rare but v aggressive
- poor prognostic factors - loder age, male, tumour >7cm, extent of disease, LN involvement, mets, leukocytosis, poor performance status, presence of acute symtoms
Reason's to treat with 131-I ablation
1) destroys residual thyroid tissue and therefore enhances sensitivity of iodine scanning and thyroglobulin
2) destroy occult microscopic carcinoma
3) detection of persisitent carcinoma (b/c such a large amount of iodine used)
Def'n of Delphian Nodes
Nodes anterior to the larnyx just above the isthmus
When treat with EBRT
- anaplastic
- significant node positive disease
- significant gross disease
- medullary thyroid and margin +, nodal disease or gross disease
- symptomatic mets
5 yr OS for papillary thyroid ca
AJCC handbook:
Stage:
1: 97%
2: 93%
3: 80%
4: 40%
5 yr OS for follicular thryoid ca
AJCC handbook:

Stage:
1: 97%
2: 90%
3: 60%
4: 40%
5 yr OS for medullary thyroid ca
AJCC handbook:

Stage:
1: 100%
2: 88%
3: 75%
4: 25%
5 yr OS for anaplastic thyroid ca
AJCC handbook:

stage 4 by definition
- 7% 5 yr OS
- median survival of 4-5 months