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The significance of unrecognized histological high‐risk features on response to therapy in papillary thyroid carcinoma measuring 1–4 cm: implications for completion thyroidectomy following lobectomy
Author(s) -
Lang Brian H.H.,
Shek Tony W.H.,
Wan Koon Y.
Publication year - 2017
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/cen.13165
Subject(s) - medicine , lymphovascular invasion , thyroidectomy , thyroid carcinoma , surgical margin , carcinoma , surgery , metastasis , thyroid , cancer
Summary Background Although lobectomy is an alternative to total thyroidectomy ( TT ) for 1–4 cm papillary thyroid carcinoma ( PTC ) without high‐risk features ( HRF s) such as aggressive histology, vascular invasion, lymphovascular invasion ( LVI ), microscopic extrathyroidal extension, positive margin, nodal metastasis >5 mm and multifocality, these HRF s are not recognized until after surgery. Therefore, the chance of completion TT being required following lobectomy might be high. We evaluated the frequency of unrecognized HRF s and how they affected the response to therapy following TT and radioiodine ( RAI ). Methods Altogether, 1513 patients were analysed. Only 1–4 cm PTC s without recognizable HRF s were included. For response‐to‐therapy evaluation, only patients who had TT and post‐ RAI ‐stimulated thyroglobulin were analysed. Patients without an excellent response were defined as having ‘incomplete response’. A multivariate analysis for incomplete response was performed. Results Of the 600 patients eligible for lobectomy, 257 (42·8%) had ≥1 unrecognized histological HRF before surgery. The prevalence of unrecognized HRF s was similar between 1‐2 cm and >2–4 cm PTC s ( P = 0·393). Of the 330 patients eligible for response‐to‐therapy evaluation, 260 (78·8%) had an excellent response while 70 (21·2%) had an incomplete response. LVI was the only independent unrecognized HRF for incomplete response ( P = 0·021). Conclusions The prevalence of unrecognized histological HRF s under the current recommendations is relatively high among 1–4 cm PTC s. Among the unrecognized histological HRF s, LVI was the only one which independently associated with an incomplete response (i.e. posing an increased risk of persistent/recurrent disease after curative surgery). These findings may have implications for patients who undergo lobectomy for 1–4 cm PTC s with no clinically recognizable HRF s under the current recommendations.