Abstract Journal Endocrine Surgery

Journal Endocrine Surgery ES001 PRE-OPERATIVE SONOGRAPHIC VOLUMETRIC ASSESSMENT PREDICTS TUMOUR SIZE AND LYMPH NODE STATUS IN PAPILLARY THYROID CANCER THOMAS PENNINGTON, MAY THWIN, LEIGH DELBRIDGE, MARK SYWAK AND STAN SIDHU University of Sydney Endocrine Surgical Unit, NSW Purpose: Papillary thyroid cancers (PTC) are three dimensional tumours, yet staging systems employ one dimensional tumour measurements. PTCs are ellipsoid in shape such that measurement of maximum diameter alone is unlikely to predict tumour volume accurately. As a recent trend towards managing smaller PTCs with observation alone has gained traction, accurate sonographic assessment of tumour size takes on renewed importance. This study examines the relationship between sonographic maximum diameter and sonographic tumour volume with correlation to histopathology and nodal status. Methodology: The Sydney University Endocrine Surgery Unit database was queried for pre-operative sonographic nodule volumetric assessment in patients with subsequently confirmed PTC. Correlation between sonographic nodule volume and maximum diameter alone and histology was performed. Results: 121 patients met the inclusion criteria and were reviewed for histological size concordance and nodal status. Preoperative ultrasound overestimated the histological tumour size 59% of the time, with a mean difference of 4.5%. The maximum US diameter alone was only able to predict the actual US nodule volume within a 10% error, 28% of the time. Overall rate of lymph node metastasis was 47%. Nodal metastasis was observed in PTCs as small as 0.25mL. Nodules with a volume between 0.25–0.85mL had the highest rate of lymph node involvement at 68%. Conclusion: Maximum diameter alone is an inaccurate marker of PTC tumour size. Furthermore, small volume tumours have high rates of lymph node involvement, necessitating accurate pre-operative volume estimation to stratify risk and guide management decisions. ES002 PD-L1 EXPRESSION IS ASSOCIATED WITH EPITHELIALMESENCHYMAL TRANSITION IN PAPILLARY THYROID CANCER MARRA AGHAJANI, NAVIN NILES, TAO YANG, TARA ROBERTS AND PAUL DESOUZA Ingham Institute for Applied Medical Research, NSW Purpose: Thyroid cancer is the most common malignant endocrine tumour, accounting for ~2.1% of all cancer diagnoses worldwide. Accumulating evidence has shown that programmed cell death-ligand 1 (PD-L1) is associated with poor prognosis and resistance to conventional anti-cancer therapies. PD-1/PD-L1 pathway blockade has demonstrated encouraging results across multiple tumour types, including thyroid cancer; however, robust and sustained responses have not yet been realised. The identification of predictive molecular-based biomarker panels is needed in order to optimise patient benefit from these novel anti-tumour agents. The purpose of this study was to investigate the correlation between PDL1 expression and epithelial-mesenchymal transition (EMT) in papillary thyroid cancer (PTC) patients. Methodology: Immunohistochemistry for e-cadherin (epithelial marker), vimentin (mesenchymal marker) and PD-L1 was performed on 74 cases of PTC. Stained cells were manually counted and analysed for clinical and histopathological correlations. Results: Of the 74 patients included in this study, 49 (66.2%) were scored as PD-L1 positive. PD-L1 positivity was significantly higher in PTC patients with mesenchymal phenotypes (p=0.012), as determined by low e-cadherin and high vimentin expression. Moreover, an older age of diagnosis was significantly associated with an EMT positive phenotype (p=0.036). Whilst tumoral PD-L1 expression was not significantly associated with DFS (p=0.053), poorer DFS was evident in PD-L1+ patients with EMT features compared to PD-L1+/EMTand PD-L1subgroups (p=0.014). Conclusion: This study demonstrates that PD-L1 overexpression in PTC is associated with EMT. Patients with EMT positive phenotype PTC may benefit from PD-1/PD-L1 blocking immunotherapy. ES003 DEVELOPMENT OF A BI-NATIONAL THYROID CANCER CLINICAL QUALITY REGISTRY LIANE IOANNOU, JONATHAN SERPELL, SUSANNAH AHERN, CINO BENDINELLI, JOANNE DEAN, JENNY GOUGH, DEAN LISEWSKI, WIN MEYER-ROCHOW, JULIE MILLER, STAN SIDHU, DUNCAN TOPLISS, DAVID WALTERS AND JOHN ZALCBERG Monash University, VIC Background: The occurrence of thyroid cancer is increasing throughout the developed world, including Australia, and since the 1990s has become the fastest increasing malignancy. In 2014, 2,693 Australians were diagnosed with thyroid cancer, with this number projected to rise to 3,300 in 2018. Objectives: To establish a bi-national clinical quality registry with the aim of monitoring and improving the quality of care provided to patients diagnosed with thyroid cancer in Australia and New Zealand. Patients & Methods: The Australian and New Zealand Thyroid Cancer Registry (ANZTCR) captures clinical data for all patients, over the age of 18 years, diagnosed with thyroid cancer, confirmed by histopathology report that have been diagnosed or treated at a contributing hospital. Data is collected by endocrine surgeons via direct data entry using a web-based interface, REDCap. Results: The ANZTCR is currently operating across sites in Victoria, New South Wales and South Australia, with over 30 sites expected to come on board in 2018 across Australia, as well as additional sites in New Zealand. A modified-Delphi process was undertaken to determine the key quality indicators to be reported by the registry and a minimum dataset was developed comprising information regarding diagnosis, pathology, surgery and 30-day follow up. Conclusion: There are very few established thyroid cancer registries internationally, yet clinical quality registries have shown valuable outcomes and patient benefits in other cancers. The ANZTCR provides the opportunity for Australia to be an international leader in this area, as well as to further understand current practice in the treatment of thyroid cancer and reasons for variation in outcomes. ES004 APPARENT LOW-RISK DIFFERENTIATED THYROID CANCERS ARE UNDER-TREATED WITH INITIAL THYROID LOBECTOMIES ONLY MAN-SHUN WONG, DANE COLE-CLARK, JAYANI JAYASEKARA, LEIGH DELBRIDGE, MARK SYWAK AND STAN SIDHU Royal North Shore Hospital, NSW Purpose: The 2015 American Thyroid Association (ATA) guidelines make recommendations for thyroid lobectomy as a viable treatment for "low-risk" differentiated thyroid cancers. There has been concern regarding these recommendations as it may initially under-treat apparent "low-risk" thyroid cancers, requiring a significant proportion to undergo a second completion procedure after final histopathological analysis. This study examines the application of these ATA guidelines to the patients of a large-volume Australian endocrine surgical unit. Methodology: A retrospective cohort analysis was performed on patients with Papillary Thyroid Cancer PTC (1-4cm) between 2013-2016. Variables such as rates of thyroid lobectomy, and subsequent completion lobectomy based on final histology were accrued. These were compared to our historical lobectomy rates. Results: Of all the PTC, 297/600 (49.5%) patients with 1-4cm nodules biopsied as Bethesda V/VI were included in the study. Based on preoperative investigations, 221/297 (74.4%) lobectomies would be recommended by the ATA guidelines as the initial treatment. Thyroid lobectomy would have been adequate treatment for 129/221 (58.4%) patients, but Editorial material and organization © 2018 Royal Australasian College of Surgeons. Copyright of individual abstracts remains with the authors. ANZ J. Surg. 2018; 88 (S1) 48–53