MON-531 Thyroid Cancer in Saudi Arabia: Clinical and Histopathological Features, Management and Outcome of a Large Series
Authors: Mukhtar Noha , Albalawi Lina Nasser , Mazi Sedra , Aljamei Hadeel Salah , Fadel Roqyah , Amer Lama Ghassan , Elsayed Tarek , AlQarni Bayan Saeed , Alnasser Layla , Alanazi Faisal , Almatar Ahmed , Alqahtani Ashwag Sultan , Bohlega Balsam Saeed , Moria Yosra , Alzahrani Ali 
Published: May 2020

Abstract
The incidence of differentiated thyroid cancer (DTC) is increasing worldwide. Most of the available data came from Western populations. Therefore, data from other populations are important for comparison and understanding of the spectrum of DTC worldwide. In Saudi Arabia, DTC is the 3rd most common cancer in general and the second most common in females after breast cancer. King Faisal Specialist Hospital and Research Centre is the main tertiary care referral center that manages the vast majority of DTC in the country. In this study, we describe the clinical and histopathological features and the management and outcome of a large series of 814 patients (pts) managed during the period Jan. 2004-Dec. 2006. Data were collected from electronic medical records. Thirty-seven pts were medullary and anaplastic thyroid cancers and 31 pts had incomplete data and were excluded from further analysis. The remaining 746 pts of DTC were studied in detail. There were 154 males (20.6%) and 592 females (79.4%). The median (range) age at the time of diagnosis was 38 years (6-83). Total thyroidectomy was performed in 719 pts (96.4%) while the other 27 pts had partial thyroid surgery. Central and/or lateral lymph node dissection was performed in 545 pts (73%).
The tumors were classic papillary thyroid cancer (PTC) in 539 (72.3%) pts, follicular variant PTC in 103 (13.8%), tall cell variant PTC in 22 (2.9%), diffuse sclerosing type PTC in 10 (1.3%), follicular thyroid cancer (FTC) in 22 (2.9%). Hurthle cell cancer in 10 pts (1.3%) and 35 (4.7%) pts with other types of TC. The median tumor size is 2.0 cm (range 0.1-13). The tumors were multifocal in 307 (41.2%), had extrathyroidal extension in 299 (40%) and lymphovascular invasion in 161 pts (21.6%). Minimal to extensive lymph node resection/dissection was performed in 545 pts (73%) and was positive in 323 pts (43.3% of total pts and 59% of those who underwent LN dissection). Distant metastases were found in 96 pts (12.9%). Using TNM staging system version 8, 602 pts (80.7%) had stage 1, 73 (9.8%) stage 2, 11 (1.5%) stage 3, 1 (0.1%) stage 4a, 37 (4.9%) stage 4b and 22 (1.9%) unstageable.
Radioactive iodine (I-131) ablation/therapy was given to 646 pts (86.6%) with a median administered activity of 147 mCi (range 14-302). Additional therapies were given to 187 pts and included additional RAI, surgeries and/or external irradiation. Over a median follow up of 7.6 yrs (0.5-13.2), the final outcome was as follows: 432 (58%) were in excellent status, 92 pts (12.3%) in an indeterminate status, 23 pts (3.1%) with biochemically incomplete status, 63 pts (8.4%) with structurally incomplete disease. Death due to DTC occurred in 31 pts (4.2%) while 103 pts (13.8%) were lost for follow up and their status is not clear.
Conclusions: Compared with data from North America and Europe, DTC in Saudi Arabia occurs at a much earlier age, is frequently metastatic at presentation and is associated with a higher mortality.