Influence of Body Mass Index and Body Surface Area on the Behavior of Papillary Thyroid Carcinoma

Background: Previous studies have examined the relationship between body mass index (BMI) and the behavior of papillary thyroid carcinomas (PTC). However, the results are inconsistent. The purpose of this study was to clarify the association between PTC behavior and anthropometric parameters including BMI and body surface area (BSA). Methods: This study retrospectively reviewed 5081 PTC patients who underwent total thyroidectomy with bilateral central neck dissection between January 2002 and June 2015. Because of sexual dimorphism in obesity, analyses were conducted separately for men and women. The World Health Organization BMI classification was used to classify patients as normal (18.5 <= BMI < 25 kg/m(2)), overweight (25 <= BMI < 30 kg/m(2)), or obese (BMI 30 kg/m(2)). Since no consensus for BSA categorization exists, enrolled patients were grouped into BSA quartiles by sex: women BSA1 (BSA < 1.52m(2)), BSA2 (1.52 <= BSA < 1.59m(2)), BSA3 (1.59 <= BSA < 1.67m(2)), and BSA4 (BSA 1.67m(2)); and men BSA1 (BSA < 1.77m(2)), BSA2 (1.77 <= BSA < 1.86m(2)), BSA3 (1.86 <= BSA < 1.96m(2)), and BSA4 (BSA 1.96m(2)). Results: In women, overweight (adjusted odds ratio [OR] = 1.187, p = 0.042) and obese (adjusted OR= 2.231, p < 0.001) were independent predictors for multiplicity. Furthermore, overweight (adjusted OR= 1.237, p = 0.012) and obese (adjusted OR= 1.789, p = 0.005) were independent predictors for extrathyroidal extension (ETE). However, higher BMI was not an independent predictor for bilaterality or central lymph node metastasis (CLNM). In addition, higher BSA-BSA3 (adjusted OR= 1.205, p = 0.049) and BSA4 (adjusted OR= 1.524, p < 0.001)was an independent predictor for multiplicity. However, higher BSA was not a predictor for bilaterality, ETE, or CLNM. In men, higher BMI and BSA were not predictors for multiplicity, bilaterality, ETE, or CLNM. Conclusions: In women with PTC, higher BMI was an independent predictor for multiplicity and ETE. Furthermore, higher BSA was an independent predictor for multiplicity. However, BMI and BSA were not predictors for the PTC behavior in men.