Potential impact of BMI on the aggressiveness of presentation and clinical outcome of Differentiated Thyroid Cancer

BACKGROUND: Obesity is a risk factor for several cancers, including differentiated thyroid cancer (DTC). Moreover, it has also been investigated as a potential risk factor for aggressiveness of DTC, but the data gathered so far are conflicting. The aim of our study was to evaluate the relationship between body mass index (BMI), aggressiveness of DTC at diagnosis, and clinical outcome. METHODS: We evaluated 1058 consecutive DTC patients treated with total thyroidectomy and enrolled at the time of first radioactive iodine (131I) treatment. Patients were divided into 4 groups based on their BMI: underweight (< 18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (≥ 30 kg/m2). Histological aggressiveness of DTC at the time of diagnosis and clinical outcome according to 2015 American Thyroid Association (ATA) guidelines were evaluated. RESULTS: No differences in histological features, ATA risk of recurrence, activity of 131I administered and prevalence of 131I avid metastatic disease after first131I treatment, have been demonstrated among the groups. Furthermore, at the end of follow up (median = 5.7 years), no differences were evident in the number of further treatments performed as well as in the clinical response. CONCLUSIONS: In our study group of Caucasian subjects, we could not demonstrate any association between BMI and aggressiveness of DTC, neither at the time of diagnosis nor during follow-up. These data indicate that postsurgical assessment and therapeutic attitude for treatment and follow-up of DTC should be based on the class of risk applied to the general population, with no concern for BMI.