Title

RETROSPECTIVE ANALYSIS OF FACTORS INFLUENCING THE DECISION BETWEEN INPATIENT OR OUTPATIENT RADIOACTIVE IODINE ABLATION/TREATMENT OF PAPILLARY THYROID MICROCARCINOMA.

OP-T-3

Trainee

Oral Presentation

Nuclear Medicine Division, Department of Radiology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand

Author(s)


Kanokwongnuwat W

Sritara C

Kositwattanarerk A

Thamnirat K

Utamakul C

Larbcharoensub N

Chamroonrat W


Background

The aim of this study was to evaluate factors that relate to the physician decision for inpatient or outpatient initial radioactive iodine (RAI) ablation/treatment of papillary thyroid microcarcinoma.

Study Design & Methods

We retrospectively included consecutive 199 patients with papillary thyroid microcarcinoma (171 women and 28 men with mean age of 52 years old) who underwent at least subtotal thyroidectomy at Ramathibodi Hospital during 2012-2017 without co-existing cancer. All patients had initial RAI ablation/treatment with (at least 3.7 GBq; 100 mCi) or without (1.1 GBq; 30 mCi) hospital admission.

Results

On the basis of RAI ablation/treatment, there were 92 (46.2%) inpatients and 107 (53.8%) outpatients. The median stimulated serum Tg levels prior RAI ablation/treatment were 1.71, 2.5, 1.23 ng/ml in the group of total patients, inpatient RAI, and outpatient RAI, respectively. The respective median tumor sizes (cm) were 0.6, 0.7 and 0.4. We found higher risk features as vascular invasion, extrathyroidal extension, microscopic not-free-margin and local/cervical nodal metastases in 13 (14.1%), 29 (31.5%), 10 (10.9%), 29 (31.5%) of 92 patients in inpatient RAI group, respectively, and in 3 (2.8%), 3 (2.8%), 5 (4.7%), 1 (0.9%) of 107 patients, in outpatient RAI group, respectively.

Conclusions

In our practice, scheduling inpatient RAI doses for patients with thyroid microcarcinoma depended on the presence of higher risk features, especially initial/first RAI ablation/treatment. Although, stimulated Tg levels and various microcarcinoma (up to 1 cm) sizes are hardly part of physician decision when preordering RAI, the higher risk features seem to relate to higher stimulated serum Tg levels and larger tumor sizes in inpatient RAI group.

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