Impact of body mass index on survival outcome in patients with differentiated thyroid cancer

Introduction: Increased body mass index is known to be associated with the high prevalence of differentiated thyroid cancers; however data on its impact on survival outcome after thyroidectomy and adjuvant therapy is scanty. Objective: We aimed to evaluate the impact of body mass index on overall survival and disease free survival rates in patients with differentiated thyroid cancers. Methods: Between 2000 and 2011, 209 patients with differentiated thyroid cancers (papillary, follicular, hurthle cell) were treated with thyroidectomy followed by adjuvant radioactive iodine-131 therapy and thyroid-stimulating hormone suppression. Based on body mass index, patients were divided into five groups; (a) <18.5 kg/m(2) (underweight); (b) 18.5-25 kg/m(2) (normal weight); (c) 26-30 kg/m(2) (overweight); (d) 31-40 kg/m(2) (obese) and (e) >40 kg/v (morbid obese). Various demographic, clinical and treatment characteristics and related toxicity and outcomes (overall survival, and disease free survival) were analyzed and compared. Results: Median follow up period was 5.2 years (0.6-10). Mean body mass index was 31.3 kg/m(2) (17-72); body mass index 31-40 kg/m(2) was predominant (89 patients, 42.6%) followed by 26-30 kg/m(2) seen in 58 patients (27.8%). A total of 18 locoregional recurrences (8.6%) and 12 distant metastasis (5.7%) were seen. The 10 year disease free survival and overall survival rates were 83.1% and 58.0% respectively. No significant impact of body mass index on overall survival or disease free survival rates was found (p = 0.081). Similarly, multivariate analysis showed that body mass index was not an independent prognostic factor for overall survival and disease free survival. Conclusion: Although body mass index can increase the risk of thyroid cancer, it has no impact on treatment outcome; however, further trials are warranted. (C) 2017 Associacao Brasileira de Otorrinolaringologia e Cirurgia Cervico-Facial. Published by Elsevier Editora Ltda.