Association Between Body Mass Index and Aggressive Features of Differentiated Thyroid Cancer

Background: Obesity is recognized as a risk factor for several types of cancers, including differentiated thyroid cancer (DTC). However, the association between obesity and aggressiveness of DTC is controversial. The aim of this study was to assess the relationship between body mass index (BMI), aggressive clinicopathological features of DTC and response to therapy in Saudi population. Methods: We evaluated 209 patients retrospectively who underwent total thyroidectomy at a referral center and diagnosed with DTC. Patients were stratified into 2 groups based on their BMI: non-obese (< 30 kg/m2), and obese (≥ 30 kg/m2). Pathological aggressiveness of DTC as well as clinical outcome were evaluated according to the 2015 American Thyroid Association (ATA) guideline. Data were described as mean ± SD and the categorical data as frequency percent. Mann Whitney test measured the difference in medians of all the metric variables and Chi-square test was applied for the categorical data to measure the intergroup difference between obese and non-obese binary dependent variable. All the inferences were carried out at 95% confidence interval in SPSS 25.0 software. Results: One-hundred twenty (57.4%) of our cohort were obese. Obesity was significantly more common in females (61.7%) than males (29.6%); (p=0.002). There were no differences in histopathological features between the non-obese and obese patients, including tumor size (2.3 ± 1.7 cm vs. 2.5 ± 2.1 cm, respectively, P-value = 0.812), extrathyroidal extension (16.9 % vs. 22.4 %, respectively, P-value=0.336), vascular invasions (25 % vs 18.4 %, respectively, P-value= 0.263) and lymph nodes metastasis (N1a 19.3 % vs 11.6 %, N1b 12.0 % vs. 10.7 % respectively, with P-value = 0.289), were shown between the two groups. In addition, no differences were evident in the ATA risk of recurrence (P-value = 0.843), TNM stage (P-value= 0.797), response to therapy (P-value= 0.252) and survival (P-value= 0.389) across the two groups. Conclusion: No association between BMI and DTC aggressiveness were found in our study population of Saudi patients. In addition, no association were demonstrated between BMI and response to therapy in DTC. These findings suggest that BMI may not be an independent risk factor for aggressiveness in DTC and that other traditional clinicopathological factors should be applied for risk assessment.