Journal of Otolaryngology-Head & Neck Surgery Volume 39, Issue 03, June 2010, Pages 284-287 Bilateral Papillary Thyroid Cancer and Associated Histopathologic Findings Euna Hwang MDCM, Michael N. Pakdaman MD, Michael Tamilia MD, FRCPC, Michael P. Hier MD, FRCSC, Martin J. Black MD, FRCSC, Louise Rochon MD, FRCPC, Richard J. Payne MD, MSc, BCom, FRCSC. Euna Hwang: Faculty of Medicine, McGill University, Montreal, Quebec; Department of Otolaryngology-Head & Neck Surgery, University of Ottawa, Ottawa, Ontario; Michael N. Pakdaman: Faculty of Medicine, McGill University, Montreal, Quebec; Massachusetts Eye and Ear Infirmary, Boston, Massachusetts; Michael P. Hier, Martin J. Black, Richard J. Payne: Department of Otolaryngology-Head & Neck Surgery and Michael Tamilia: Department of Endocrinology, and Louise Rochon: Department of Pathology, Jewish General Hospital, Montreal, Quebec. Presented at the annual meeting of the American Academy of Otolaryngology-Head and Neck Surgery, Chicago, IL, September 21–24, 2008. ABSTRACT ( Email Abstract ) OBJECTIVE: To determine the incidence of bilateral papillary thyroid cancer (PTC) at total thyroidectomy (TT) and compare demographic risk factors (gender and age) and histopathologic findings (tumour size, extrathyroidal extension [ETE], T staging, and multifocality) between patients with PTC in both thyroid lobes and those with PTC limited to the ipsilateral lobe and/or isthmus. DESIGN: Retrospective study. SETTING: University teaching hospital. METHODS: The pathology results of 1047 consecutive patients who underwent TT between 2002 and 2008 were reviewed. Statistical significance was obtained using the chi-square test. MAIN OUTCOME MEASURES: Incidence of bilateral PTC and its association with demographic risk factors and histopathologic findings. RESULTS: Among 592 patients with PTC, 13.2% had bilateral PTC and 86.8% had unilateral and/or isthmian PTC. Bilaterality was present in 12.4% of women and 16.7% of men (p = .24) and in 12.9% of patients aged ≥ 45 years and 13.5% < 45 years (p = .83). Bilateral PTC was found in 12.6% of patients with a primary tumour ≤ 2 cm and 13.5% > 2 cm (p = .75); 23.6% of tumours with ETE demonstrated bilaterality compared to 9.7% without (p < .0001), and 8.7% of pT1 (p = .08), 9.2% of pT2 (p = .02), 23.0% of pT3 (p < .0001), and 12.5% of pT4 (p = .87) tumours were bilateral, respectively. Among bilateral PTC patients, 43.2% had multifoci in at least one lobe compared to 6.4% when nonbilateral (p < .0001). CONCLUSIONS: After TT, 13.2% of patients had bilateral PTC. No significant correlation was established between bilaterality and gender, age, and tumour size. Bilaterality was more commonly found in patients with ETE, advanced T stage, and at least one multifocal lobe. Translated Abstract Sommaire OBJECTIF: L'étude avait pour objectifs de déterminer l'incidence du cancer papillaire de la thyroïde (CPT), bilatéral au moment de la thyroïdectomie totale (TT), et de comparer les facteurs de risque démographiques (sexe, âge) ainsi que les constatations histopathologiques (grosseur de la tumeur, extension extrathyroïdienne [EE], stade T, multifocalité) entre les patients atteints d'un CPT touchant les deux lobes de la thyroïde et les patients atteints d'un CPT ne siégeant que dans le lobe ipsilatéral et/ou dans l'isthme. TYPE D'éTUDE: Il s'agit d'une étude rétrospective. LIEU: L'étude a été menée dans un hôpital d'enseignement universitaire. MéTHODES: Nous avons passé en revue les résultats des examens histopathologiques effectués chez 1047 patients consécutifs ayant subi une TT entre 2002 et 2008. Le test du chi carré a permis d'obtenir des résultats statistiquement significatifs. PRINCIPAUX CRITàRES D'éVALUATION: