Impact of body mass index on survival outcome in patients with differentiated thyroid cancer / Impacto do índice de massa corporal sobre o desfecho de sobrevida em pacientes com câncer diferenciado de tireoide

Abstract 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/m2 (underweight); (b) 18.5-25 kg/m2 (normal weight); (c) 26-30 kg/m2 (overweight); (d) 31-40 kg/m2 (obese) and (e) >40 kg/m2 (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/m2 (17-72); body mass index 31-40 kg/m2 was predominant (89 patients, 42.6%) followed by 26-30 kg/m2 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.

Resumo Introdução Sabe-se que o aumento do índice de massa corpórea está associado à alta prevalência de câncer diferenciado de tireoide; entretanto, os dados sobre seu impacto no desfecho de sobrevivência após tireoidectomia e terapia adjuvante são escassos. Objetivo Objetivou-se avaliar o impacto do índice de massa corpórea nas taxas de sobrevida global e sobrevida livre de doença em pacientes com câncer diferenciado de tireoide. Método Entre 2000 e 2011, 209 pacientes com câncer diferenciado de tireoide (papilar/folicular/de células de Hurthle) foram tratados através de tireoidectomia, seguida de tratamento com iodo radioativo-131 adjuvante e supressão de hormônio estimulante da tireoide. Com base no índice de massa corpórea, os pacientes foram divididos em cinco grupos; (a) < 18,5 kg/m2 (baixo peso); (b) 18,5-25 kg/m2 (peso normal); (c) 26-30 kg/m2 (sobrepeso); (d) 31-40 kg/m2 (obesos) e (e) > 40 kg/m2 (obesos mórbidos). Várias características demográficas, clínicas e de tratamento e toxicidade associada e desfechos (sobrevida global e sobrevida livre de doença) foram analisadas e comparadas. Resultados O período médio de acompanhamento foi de 5,2 anos (0,6-10). O índice de massa corpórea médio foi de 31,3 kg/m2 (17-72); o índice de massa corpórea de 31-40 kg/m2 foi predominante (89 pacientes, 42,6%), seguido por 26-30 kg/m2, observado em 58 pacientes (27,8%). Observaram-se 18 recidivas locorregionais (8,6%) e 12 metástases distantes (5,7%). As taxas de sobrevida livre de doença e sobrevida global de 10 anos foram de 83,1% e 58,0%, respectivamente. Não foi encontrado impacto significativo do índice de massa corpórea nas taxas de sobrevida global ou sobrevida livre de doença (p = 0,081). Da mesma forma, a análise multivariada mostrou que o índice de massa corpórea não foi um fator prognóstico independente para sobrevida global e sobrevida livre de doença. Conclusão Embora o índice de massa corpórea possa aumentar o risco de câncer de tireoide, ele não tem impacto no resultado do tratamento; contudo, outros estudos são necessários.

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) <18.5kg/m2 (underweight); (b) 18.5-25kg/m2 (normal weight); (c) 26-30kg/m2 (overweight); (d) 31-40kg/m2 (obese) and (e) >40kg/m2 (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 5.2years (0.6-10). Mean body mass index was 31.3kg/m2 (17-72); body mass index 31-40kg/m2 was predominant (89 patients, 42.6%) followed by 26-30kg/m2 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.