Sex-dependent impact of obesity on aggressiveness of papillary thyroid cancer.

[PURPOSE] To investigate the impact of body mass index (BMI) on the aggressiveness of papillary thyroid cancer (PTC).

[METHODS] A total of 1720 PTC patients with total thyroidectomy or lobectomy, from January 2017 to April 2020, were retrospectively evaluated. Based on BMI, they were divided into two groups, as follows: control (CON, < 24 kg/m) and overweight and obesity (OB, ≥ 24 kg/m), each sex being analyzed separately.

[RESULTS] In the whole cohort, the OB group had significantly higher rates of extrathyroidal extension (21.5 vs. 16.8%, p = 0.013), multifocality (43.2 vs. 37.7%, p = 0.018), and BRAF-V600E mutation (82.9 vs. 79.3%, p = 0.015) than the CON group. In males, the OB group had increased rates of tumor size over 1cm (54.4 vs. 42.7%, p = 0.008), extrathyroidal extension (24.9 vs. 12.4%, p = 0.001), and multifocality (42.7 vs. 33.5%, p = 0.038). The OB group had significantly higher adjusted odds ratios (ORs) of 1.63 (1.14-2.33, p = 0.008), 2.12 (1.26-3.57, p = 0.005), and 1.56 (1.07-2.29, p = 0.022) for tumor size over 1cm, extrathyroidal extension, and multifocality compared with CON. Additionally, overweight and obesity were analyzed alone and the rates of extrathyroidal extension (30/100, 30.0%, p = 0.001) and tumor size over 1cm (65/100, 65.0%, p = 0.001) were significantly higher in the obesity group than in the overweight and CON groups. The obesity group had robust higher adjusted ORs of 2.51(1.50-4.20, p < 0.001), 2.93 (1.50-5.73, p = 0.002) and 1.89 (1.11-3.22, p = 0.020) for tumor size over 1cm, extrathyroidal extension, and multifocality compared with CON.

[CONCLUSIONS] Overweight and obesity were predominant independent risk factors for PTC aggressiveness in males. These data indicated that the therapeutic treatment should be based on risk stratification by BMI in males.