Thyroid Cancer

Created by ryangcarlson 

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Ch 11 - Hansen

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

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