Endocrine Abstracts (2013) 32 P1096 | DOI: 10.1530/endoabs.32.P1096

Radioactive iodine therapy in papillary thyroid carcinomas staged as T1

Pedro Marques, Daniel Macedo, Joana Pereira, Margarida Vieira, Valeriano Leite & Maria Bugalho

Portuguese Institute of Oncology, Lisboa, Portugal.

Introduction: 131I therapy in patients with papillary thyroid carcinomas (PTC) ≤2 cm and without extrathyroidal extension (T1) depends on multifactorial analysis: age, multifocality, histological criteria, lymph node or systemic metastasis. The study purposes were analyze PTC-T1 and compare the groups treated only with surgery vs combined therapy (surgery and 131I).

Methods: Retrospective analysis of clinical files of PTC-T1 patients diagnosed between 2002 and 2006, and followed in Endocrinology Department of Portuguese Institute of Oncology, Lisbon. Patients were identified through South Regional Cancer Registry.

Results: A 178 PTC-T1 were identified. The mean age at diagnosis was 47.6 years (9–79). 85.9% were female (F/M=6.1:1). Mean tumour diameter was 1.2 cm (50% were T1a, meaning ≤1 cm). 4.5% had aggressive histological variant; 32.6% were multifocal; 5.1% had angioinvasion; 16.9% and 2.2% had lymph node and lung metastasis, respectively. 5.6% had positive surgical margins. Mean follow-up time was 71 months (±23).

From 178 PTC-T1, 109 patients were submitted to 131I therapy (72.2%). 65.1% were T1b; 55% had more than 45 years, 44% were multifocal; 7.4% had aggressive histological variant; 8.3% had angioinvasion; 26.6% had neck lymph node metastasis and 3.7% had lung metastasis. 87.1% are considered in complete remission. Hypothyroidism pre-131I was achieved by thyroid hormone withdrawal in 78.9% cases and by rhTSH stimulation in the remaining; TSH level at radioiodine therapy was considered ‘insufficient’ (<30 μUI/ml) in 19.1% (all in the former group). One hundred and thirty-two therapies were administered (activities ranging between 50 and 155 mCi).

From the 69 cases treated only with surgery, none presented risk histological criteria, namely aggressive histological variant, angioinvasion, nodal or systemic metastasis. All are considered in complete remission.

Conclusion: Generally, PTC-T1 are associated with good prognosis. In the absence of metastasis and/or aggressive histological criteria, the benefit of 131I therapy is doubtful. A trend to reduce 131I therapies was noticed in this study.

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