The Risk of overlooking thyroid cancer in radioiodine treatment

of hyperthyreosis and goiter

Anders Vej-Hansen (1), Lars Thorbjørn Jensen (2),

Kaj Siersbæk-Nielsen (3) og Birte Nygaard (1)

1) Dep. of Endocrinology, Herlev Hospital, 2) Dep. of Clinical Fysiology, Glostrup Hospital, 3) Dep. of Endocrinology, Frederiksberg Hospital, Denmark

Introduction

• About 3,000 patients are treated with radioiodine in Denmark for thyroid diseases each year

• Alternative treatment is surgery but radioiodine is more gentle

• Evaluation strategy includes bloodsamples and a scintiscan

Previous studies

Study N - follow up Treatment No. cancers %/SMR/SIR

Ron et al1998Death c.thyr.Tox

35.593 – 21 years23.54010.8761.177

AllRadioiodineSurgeryMedicine

2925 (12/<4 years)40

0,08 % 2,8 (SMR)0,11 % 3,9 (SMR)0,04 % 1,1 (SMR)0 % 0 (SMR)

Dobyns et al 1974Develop c.thyr.Tox

34.684 – ? years21.71411.7321.238

AllRadioiodineSurgeryMedicine

86 (10 dead)28 (9/1. year)54 (18 mikr.c.)4

0,25 %0,19 %0,50 %0,30 %

Augusti et al2000Develop c.thyr.Tox

6.647 – 7 years Radioiodine 10 0,15%No difference from background population

Purpose

• To evaluate if the evaluation strategy is good enough to exclude thyroid cancer

Materials and methods

• We collected information about all patients treated with radioiodine in 3 centre hospitals in Copenhagen

• Information was compared with information on reported thyroid cancers in the national cancer register

Results I

  N (%) Follow upYears, months

No. doses Total doses (MBq)

All 4,474 9.0 1.38 534

Toxic nodular 2,653 (59) 8.2 1.35 534

Toxic diffuse 732 (16) 9.10 1.34 448

Nontoxic nodular 718 (16) 9.2 1.53 646

Results II

  No. cancers

Expected no. (backgr.pop.)

SIR(backgr.pop.)

P

All 8 0.88 9.1 < 0,05

Toxic nodular 6 0.47 12.8 < 0,05

Toxic diffuse 1 0.16 12.5 ns

Nontoxic nodular 1 0.14 7.1 ns

Description of the cancers

No. Goiter Age Time to Time to AgeSex -type RI cancer death death Patology

1 M Tox dif 61,2 -6,11- -0,5- 68,6 Anaplastic2 F Tox nod 82,8 -0,2- -0,2- 83,0 Unknown3 F Tox nod 80,7 -4,5- -3,5- 88,5 Folliculary 4 M Tox nod 73,9 -0,8- -0,2- 74,7 Anaplastic5 F Tox nod 77,7 -7,0- -4,10- 89,5 (alive) Papillifery6 F Tox nod 75,9 -2,8- -2,0- 80,5 Anaplastic7 M Atox nod 59,8 -4,5- -0,1- 64,2 Folliculary8 F Tox nod 53,9 -4,2- -1,8- 59,7 (alive) Papillifery

Discussion

• We have found more cancers than expected from the background population

• The cancer incidence is at the same level as earlier described in studies of patients with hyperthyreosis treated with medicine, surgery or radioiodine

Previous studies

Study N - follow up Treatment No. cancers %/SMR/SIR

Ron et al1998Death c.thyr.Tox

35.593 – 21years23.54010.8761.177

AllRadioiodineSurgeryMedicine

2925 (12/<4 year)40

0,08 % 2,8 (SMR)0,11 % 3,9 (SMR)0,04 % 1,1 (SMR)0 % 0 (SMR)

Dobyns et al 1974Develo. c.thyr.Tox

34.684 – ? years21.71411.7321.238

AllRadioiodineSurgeryMedicine

86 (10 death)28 (9/1. year)54 (18 mikr.c.)4

0,25 %0,19 %0,50 %0,30 %

Augusti et al2000Develo. c.thyr.Tox

6.647 – 7 years Radioiodine 10 0,15%No difference from backgroun population

Vej-Hansenet al 2006Develo. c.thyr.Tox+Atox

4.474 – 9 years Radioiodine 8 (2/1. year, 3/<4 years)

0,18 % 9,1 (SIR)

Conclusion

• In this study it seems that we don´t overlook cancer if we use scintiscan, and when it shows a cold nodule, we do a biopsy

• This is also the evaluation of patients with nontoxic goiter

Thank You!!!

Anders Vej-Hansen, Lars Thorbjørn Jensen, Kaj Siersbæk-Nielsen og Birte Nygaard