OP96 – Low incidence of NIFTP in Asian practice: a multi-institutional study from 6 countries

      Bychkov, Andrey1; Hirokawa, Mitsuyoshi2; Jung, Chan Kwon3; Liu, Zhiyan4; Zhu, Yun5; Hong, SoonWon6; Satoh, Shinya7; Lai, Chiung-Ru8; Huynh, Lien9; Kakudo, Kennichi10 1 Department of Pathology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand 2 Department of Diagnostic Pathology and Cytology, Kuma Hospital, Kobe, Japan 3 Department of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, South Korea 4 Department of Pathology, Shandong University School of Medicine, Shandong, China 5 Department of Pathology, Jiangsu Institution of Nuclear Medicine, Wuxi, Jiangsu Province, China 6 Department of Pathology, Yonsei University, College of Medicine, Seoul, South Korea 7 Department of Endocrine Surgery, Yamashita Thyroid and Parathyroid Clinic, Fukuoka, Japan 8 Department of Pathology, Taipei Veterans General Hospital, Taipei, Taiwan 9 Department of Pathology, Da Nang Hospital, Danang, Vietnam 10 Department of Pathology, Nara Hospital, Kindai University Faculty of Medicine, Nara, Japan   Background/ Purpose: The recent introduction of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) to replace noninvasive encapsulated follicular variant of papillary thyroid carcinoma (eFV-PTC) is expected to have significant implications for patients and clinicians. The authors of seminal paper reported an 18.6% mean incidence of NIFTP based on the findings from the several Italian and American institutions (1). Objectives: To establish rate of NIFTP in Asian practice. Methods: We collected data on the NIFTP incidence from the 9 institutions from 6 Asian countries. FV-PTC cases were categorized as infiltrative, encapsulated invasive, or encapsulated noninvasive (NIFTP). The latter was applied only under strict diagnostic criteria proposed by Nikiforov et al. (1) Results: A total of 1,070 cases of FV-PTC were identified after screening of 26,604 cases of PTC. Slide review demonstrated a very low incidence of NIFTP (mean – 1.5%, range 0–4.7%), more than ten times less than the Western series. FV-PTC (mean – 6.3%, range 2.2–9.8%) and eFV-PTC (mean – 3.1%, range 0.7–5.5%) rates were much lower than in Western experience, e.g. 37.9% and 24% for FV-PTC and eFV-PTC, respectively (1). Discussion & Conclusion: Our findings may have an important impact for epidemiological studies on thyroid cancer reclassification. Worldwide estimates of patients affected by NIFTP and cost benefits of the reclassification need to be adjusted with regard to the low NIFTP rate in Asia. Concerning the cytological diagnosis of thyroid nodules, we expect only a minor impact of NIFTP on risk of malignancy for thyroid nodules in Asian practice.   References:
    1. Nikiforov YE, Seethala RR, Tallini G, et al. Nomenclature revision for encapsulated follicular variant of papillary thyroid carcinoma: A paradigm shift to reduce overtreatment of indolent tumors. JAMA oncology 2016; 2:1023-9.


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