The aim of this study was to investigate the prognostic significance of BRAFV600E in cell-free (cf) DNA (cfBRAFV600E) and lesion tissues (ltBRAFV600E) in pediatric Langerhans cell histiocytosis (LCH). This study included a total of 140 patients with successfully detected cfBRAFV600E and ltBRAFV600E at diagnosis. Treatment response at week 6 was correlated with both cfBRAFV600E and ltBRAFV600E Moreover, the patients with positive cfBRAFV600E had a much lower 3-year progression-free survival (PFS) rate and a higher progression/reactivation rate than those with negative cfBRAFV600E (47.1% ± 7.6% vs. 78.4% ± 5.1%, P < 0.0001; 44.6% vs. 19.0%, P = 0.001, respectively). However, no significant difference was found in the 3-year PFS rate or progression/reactivation rate between patients with positive and negative ltBRAFV600E (P = 0.348 and 0.596, respectively). In addition, after patients were divided into group A (both cfBRAFV600E and ltBRAFV600E positive, n = 56), group B (ltBRAFV600E positive and cfBRAFV600E negative, n = 28), and group C (both cfBRAFV600E and ltBRAFV600E negative, n = 56), there was a significant difference in the 3-year PFS rate and progression/reactivation rate among the three groups (47.1% ± 7.6%, 92.9% ± 6.1%, and 72.2% ± 6.1%, P < 0.001; 44.6%, 3.6%, and 26.8%, P < 0.001, respectively). In the multivariate analysis, cfBRAFV600E and age at diagnosis remained independent prognostic factors for 3-year PFS in childhood LCH. Therefore, cfBRAFV600E was more closely associated with important clinical characteristics, treatment response at week 6, and prognosis than ltBRAFV600E.
©2021 American Association for Cancer Research.