Decline in Radioiodine Use But Not Total Thyroidectomy in Thyroid Cancer Patients Treated in United Arab Emirates- A Retrospective Study

The aim of this study is to assess the trend of clinicopathological features and treatment modalities in patients with thyroid cancer (TC) in the largest oncology center in the United Arab Emirates (UAE).

This study was conducted in Tawam hospital (TWM), which provides tertiary care services to patients in the UAE. It is the only center delivering radioactive iodine (RAI) therapy and radiotherapy in Al Ain city. Most TC patients are followed in designated TC clinics within the endocrinology division or less commonly through other clinics (surgery, radiation, or medical oncology). The hospital runs monthly multidisciplinary team-based discussions on patients with TC, wherein decisions regarding RAI treatment and dose selection are determined jointly by nuclear medicine physicians and endocrinologists.

We retrospectively evaluated all patients with TC presenting to TWM during the period of September 2008 and December 2018. The beginning of data collection (September 2008) reflects the inception time of electronic medical records (EMRs) use in the hospital. Cases of TC were extracted from the EMRs using the International Classification of Disease 9 & 10 codes (193 & c73). Other variables were demographic information, year of diagnosis, type of TC, histopathological subtype, lymph node (LN) involvement, type of thyroid surgery, use of RAI treatment, and radiation therapy. The extent of surgery, the exact details of histopathology, and the RAI dose were retrieved from the respective specialty reports. Tumor staging was reported according to the 8th edition of the American joint committee on cancer (AJCC)/TNM staging system [16]. Those with incorrect pathological diagnosis, incomplete data, or noninvasive follicular type PTC were excluded.

The data were extracted using Microsoft Excel 2015 and imported into Stata 16.0 for statistical analysis. Continuous variables were described using means and standard deviations (±SD). Categorical variables were described as frequency distributions. Variables of clinical features and management were cross tabulated with the year of diagnosis and exact logistic and ordinal logistic regressions were performed to analyze the annual trend in features and management of TC as appropriate. The results of relative trend were reported as odds ratio (OR) with an overall ptrend. The OR=1 indicated no change over years, OR <1 indicated a decline, while OR >1 indicated an increase over years. Simple and multiple logistic regression analysis were performed to assess the unadjusted and adjusted association of management of TC (RAI, surgical management) with age, gender, nationality, year of diagnosis, tumor subtype, and other co-variates. The results of simple and multiple logistic regression were reported as odd ratios (OR) and adjusted odds ratios (AOR) respectively with their corresponding 95% confidence intervals (CI) and p-values.