BRAF V600E confers male sex disease-specific mortality risk in patients with papillary thyroid cancer

Abstract

[Purpose]: To test whether the prognostic risk of male sex in papillary thyroid cancer (PTC) is determined by BRAF V600E and can thus be stratified by BRAF status. [Patients and Methods]: We retrospectively investigated the relationship between male sex and clinicopathologic outcomes in PTC, particularly mortality, with respect to BRAF status in 2,638 patients (male, n = 623; female, n = 2,015) from 11 centers in six countries, with median age of 46 years (interquartile range, 35-58 years) at diagnosis and median follow-up time of 58 months (interquartile range, 26-107 months). [Results]: Distant metastasis rates in men and women were not different in wild-type BRAF PTC but were different in BRAF V600E PTC: 8.9% (24 of 270) and 3.7% (30 of 817; P = .001), respectively. In wild-type BRAF PTC, mortality rates were 1.4% (five of 349) versus 0.9% (11 of 1175) in men versus women (P = .384), with a hazard ratio (HR) of 1.59 (95% CI, 0.55 to 4.57), which remained insignificant at 0.70 (95% CI, 0.23 to 2.09) after clinicopathologic multivariable adjustment. In BRAF V600E PTC, mortality rates were 6.6% (18 of 272) versus 2.9% (24 of 822) in men versus women (P = .006), with an HR of 2.43 (95% CI, 1.30 to 4.53), which remained significant at 2.74 (95% CI, 1.38 to 5.43) after multivariable adjustment. In conventional-variant PTC, male sex similarly had no effect in wild-type BRAF patients; mortality rates in BRAF V600E patients were 7.2% (16 of 221) versus 2.9% (19 of 662) in men versus women (P = .004), with an HR of 2.86 (95% CI, 1.45 to 5.67), which remained significant at 3.51 (95% CI, 1.62 to 7.63) after multivariable adjustment. [Conclusion]: Male sex is a robust independent risk factor for PTC-specific mortality in BRAF V600E patients but not in wild-type BRAF patients. The prognostic risk of male sex in PTC can thus be stratified by BRAF status in clinical application.