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Consensus and controversy of

radioiodine and PET (orPET/CT)

in the management of well-differentiated thyroid cancer

彰濱秀傳醫院核子醫學科洪光威

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American Thyroid Association Guidelines

Thyroid. 2006 Feb;16(2):109-42.

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1. Complete ablation is the first goal

2. Tg is the main tool for follow-up (Tg-Ab)

3. 131I-DxWBS usually unnecessary

4. rhTSH in substitution of T4 withdrawal for

Dx or remnant ablation

5. Complementary roles for RxWBS and FDG-

PET

Consensus

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1. High or low dose for ablation?

Clinical Medicine & Research; Volume 5, Number 2: 87-90, 2007

• Successful ablation rate:

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Eur J Nucl Med (1987) 12:500-502

We therefore recommend a 30 mCi ablation dose for all

patients with differentiated thyroid cancer after surgical

thyroidectomy, followed by a 300 mCi treatment dose in pT2-

3N1M x or pT2-3N x M1 patients, while in pT2-3NoMo lowdose ablation will be a sufficient treatment.

7/10

7/10

8/107/10

Effect

300

300

150150

2nd Rx

3010 pT2-3NxM1

30010

100103010 pT2-3NoMo

1st RxNo.

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• Side effect:

Incidence of radiation thyroiditis and thyroid remnantablation success rates following 1110 MBq (30 mCi)

and 3700 MBq (100 mCi) post surgical I-131 ablation

therapy for differentiated thyroid carcinoma.

Clin Endocrinol (Oxf). 2008 Apr 12.

1. Incidence and severity of radiation thyroiditis following I-131 remnant

ablation therapy is directly related to thyroid remnant I-131 uptake.

(p=<0.0001)

2. Severe thyoriditis was only seen with remnant I-131 uptake >2 mCi.

3. As 30 mCi I-131 is associated with a significantly lower frequency of

thyroiditis (12% and 27%, p=0.02), but similar remnant ablation rate to 100

mCi (76% and 84% , p=NS).

4. It warrants consideration for thyroid remnant ablation particularly in

patients with low risk disease.

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Radioiodine lobar ablation as an alternative to

completion thyroidectomy in patients withdifferentiated thyroid cancerC.S. BAL,* A. KUMAR and G.S. PANT

• The mean 24 h radioiodine neck uptake at the first visit was 17.2 ± 7.3%

(4.4~34%).

• Low doses of radioiodine (15~60 mCi, 31.8 ± 11.7) were administered tothe patients;

• The thyroid lobe was completely ablated in 53 patients (56.9%) after onedose; and cumulative ablation rate was 92.1% after two doses.

• 15 patients (16.1%) complained of throat discomfort and neck pain. All ofthem were managed with mild analgesics except three patients whoneeded additional oral prednisolone

Nuclear Medicine Communications 2003, 24, 203± 208

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• Successful ablation rate: high low

• Long-term benefit: ?

• Side effect: low

• Radiation burden: low

• Cost: low

• Convenience: low

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Considerations

• High dose:

– Low or high risk disease

– Be careful for large remnant

• Low dose:

– Low risk disease

– Large remnant

– 1st ablation for high risk

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2. Fractionated dose or not ?

Clin Nucl Med. 1990 Oct;15(10):676-7

Arad E, Flannery K, Wilson GA, O'Mara RE.

Fractionated doses of radioiodine for ablation of

postsurgical thyroid tissue remnants.

1. Ablation was achieved in 9 out of 12 patients treated in a fractionated

manner (a 75% success rate), whereas in 16 out of 20 patients given a

single dose the thyroid remnants were completely eradicated (an 80%

success rate).

2. That the use of split, smaller doses administered at weekly intervals on

an ambulatory basis presents a reasonable alternative for ablation ofpostsurgical, residual-functioning thyroid tissue.

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Comparison of the Effectiveness Between a Single

Low Dose and Fractionated Doses of Radioiodine in

Ablation of Post-operative Thyroid Remnants

Guang-Uei Hung, Shih-Te Tu, Iuan-Sheng Wu, and Kwang-Tao Yang

1. Successful ablation was obtained in 20 of 38 patients (52.6%)

treated with a single low dose compared with 14 of 21 patients(66.7%) treated in a fractionated manner. (P = 0.296).

2. As the fractionated-dose protocol has the drawbacks of a much

longer hypothyroid state and a higher total expense, we suggest

that a single low dose is more feasible than fractionated doses for

outpatient ablation therapy.

Jpn J Clin Oncol 2004;34(8)469 –471

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Decreased uptake after fractionated ablative doses

of iodine-131

Hurng-Sheng Wu, Huey-Herng Hseu, Wan-Yu Lin, Shyh-Jen Wang,

Yao-Chi Liu

Eur J Nucl Med Mol Imaging (2005) 32:167 –173

1. The mean uptake of 131I was 2.73% 7 days after the first

administration, and decreased significantly to 0.26% 7 days after the

second administration. The mean decrease was as high as 80.7%.

2. In the two patients with lung metastases, no definite evidence of

decreased uptake was noted.

3. The use of fractionated ablative doses of 131I is not to be

recommended in patients without lung metastases.

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There was a 92.8% decrease in 131I

uptake between these two applications(from 0.732% to 0.053%).

There was a 70.8% increase in 131I

uptake between these two

applications (from 0.024% to 0.041%).

Park et al., visual reduction in uptake was seen in 15 of 24 thyroid remnants

or cervical lymph node metastases after 111 –370 MBq 131I but in only one of

11 distant metastases.

Eur J Nucl Med Mol Imaging (2005) 32:167 –173

Thyroid 1994;4:49 –54.

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Considerations

• Stunning effect:

– True for remnants

– Not true for metastases ?

• Side effect: yes/not

• Convenience: yes/not

• Cost: not• Alternative protocol

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Treatment of cervical nodal or

nonoperable distant metastases ?

Recombinant human TSH-aided radioiodine treatment of

advanced differentiated thyroid carcinoma: a single-

centre study of 54 patients.

1. The response to rhTSH-aided and WTH-aided treatment was similar in

52% of 44 evaluated patients, superior with rhTSH in 27% and superior

with WTH in 16% patients.

2. Comparison is limited due to a greater number of courses and

cumulative activity of 131I administered under WTH.

Jarzab B, Handkiewicz-Junak D, Roskosz J, et al.

Eur J Nucl Med Mol Imaging. 2003;30:1077 –1086.

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T4 withdrwal T4 withdrwalThyrogen

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rhTSH Stimulation Before Radioiodine Therapy in

Thyroid Cancer Reduces the Effective Half-Life of 131I

Menzel C, Kranert WT, Döbert N, et al:

1. The effective half-life of 131I was significantly prolonged after

endogenous stimulation (e.g., 0.43 d for group A vs. 0. 54 d forgroup B, P 0.001) than rhTSH-stimulated manner.

2. This is mainly due to a reduced renal iodine clearance in the

hypothyroid state.

J Nucl Med 2003; 44:1065 –1068

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Considerations

„„Compassionate‟‟ use:

patients with hypopituitarism who cannot

achieve adequate serum TSH levels after WTH patients with serious comorbidities, such as

older patients suffering from heart disease,

poorly controlled hypertension, and/or

depression, in whom hypothyroidism would be

potentially hazardous

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4. Discontinuing T4 with Thyrogen?

Iodine excretion during stimulation with rhTSH in

differentiated thyroid carcinoma.

Löffler M, Weckesser M, Frenzies C, et al.

1. L-thyroxine, which contains 65.4% of its molecular weight in iodine, is a

substantial source of iodine intake is maintained during rhTSH stimulation.

2. Iodine excretion was higher in patients under rhTSH-stimulation (75 micro

g/l) than after T4 withdrawal (50 micro g/, p <0.027).

3. This may indicate an increased iodine pool in rhTSH-stimulated patients,thus limiting the sensitivity of radioiodine scanning to the level of

endogenous stimulation

Nuklearmedizin. 2003 Dec;42(6):240-3.

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Radioiodine treatment with 30 mCi after recombinant

human thyrotropin stimulation in thyroid cancer:

effectiveness for postsurgical remnants ablation and

possible role of iodine content in L-thyroxine in the outcomeof ablationBarbaro D, Boni G, Meucci G, et al.

1. We have evaluated the effectiveness of stimulation by rhTSH for

radioiodine ablation of postsurgical remnants, stopping L-T4 the day

before the first injection of rhTSH and restarting L-T4 the day after (131)I.

2. The percentage of ablation was 81.2% in patients treated by rhTSH

withdrawal, and 75.0% in patients treated by L-T4 withdrawal,

respectively.

3. No patient experienced symptoms of hypothyroidism during the 4 d of L-T4 interruption, and serum T4 remained in the normal range.

4. Urinary iodine was 47.2 +/- 4.0, 38.6 +/- 4.0, and 76.4 +/- 9.3 microg/liter

for rhTSH withdrawl, L-T4 withdrawal, and control groups (P = 0.21 vs.

the second group, P = 0.019 vs. control group).

J Clin Endocrinol Metab 88: 4110 –

4115, 2003

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5. TSH stimulation for FDG-

PET(PET/CT) ?

Eur J Nucl Med Mol Imaging 29:641-647, 2002

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Max SUV : 26.1 (PET/CT study was performed under TSH stimulation)

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The influence of I-131 therapy on FDG uptake

in differentiated thyroid cancer

Guang-Uei Hung, Kwo-Whei Lee, Pei-Yung Liao, Li-Heng

Yang, Kwang-Tao Yang

Ann Nucl Med (2008) 22:481 –485

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Ann Nucl Med (2008) 22:481 –485

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Considerations

Overcome “stunning” from I-131 Rx:

1. Wait 3~4 months after I-131 Rx

2. Immediately after I-131 scan (TSHstimulation status) ?

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Thank you for your attention!

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