Management of precocious puberty in girls with McCune–Albright syndrome using letrozole

Abstract

Objective To evaluate the safety and efficacy of letrozole in girls with progressive precocious puberty (PP) associated with McCune-Albright syndrome (MAS). Design Monocentric retrospective cross-sectional and longitudinal study of consecutive patients. Patients Ten MAS patients treated at Peking Union Medical College Hospital between September 1999 and December 2017 were retrospectively reviewed; those with complications due to PP were followed. Results The mean age at letrozole initiation was 4.5 ± 2.6 years, while the mean duration of treatment was 3.3 ± 2.4 years. Letrozole was highly effective at decreasing the rate of skeletal maturation, with a significant decrease in the bone age-to-chronological age (BA/CA) ratio from 1.9 ± 1.1 pre-treatment to 1.5 ± 1.2 on letrozole treatment (P = 0.016). Moreover, growth velocity Z-scores declined from 0.41 ± 0.5 to -0.2 ± 0.31 with treatment (P < 0.001). Predicted adult height Z-scores increased significantly from -2.03 ± 2.33 at baseline to 1.13 ± 0.84 following treatment initiation (P = 0.029). Moreover, vaginal bleeding declined significantly on letrozole. Conclusions Our findings suggest that letrozole may be an effective therapy in some girls with MAS, as treatment results in improved BA/CA ratio, growth velocity and predicted adult height. Possible adverse effects include nettle rash.