Anthropometric measurements of children with neurofibromatosis type I: impact of plexiform neurofibroma volume and treatment.

Background: In children and adolescents/young adults (CAYA) with neurofibromatosis type I (NF1), associations between anthropometric measurements, plexiform neurofibroma (pNF) tumor volume (TV), and treatment history are unknown.

Methods: We retrospectively investigated anthropometrics in CAYA on the National Cancer Institute (NCI) NF1 Natural History Study who had pNF TV assessed by imaging (n = 106). We determined CDC height/weight percentiles and estimated Preece-Baines (PB) height growth curve parameters. We evaluated variables that could impact height/weight including: (1) pNF volume, (2) pNF directed therapy, and (3) serum IGF-1.

Results: 23% of males and 20% of females had height <5th percentile; 13% of males had weight <5th percentile. Estimated median final adult height for males was 171.6 cm (CDC 23rd percentile) and for females was 156.2 cm (CDC 14th percentile). Inverse associations between height and weight percentiles and pNF volume were observed (Spearman's r = -0.277, -0.216, respectively). Estimated median final height was not meaningfully affected by patients who received pNF-directed treatment with MEK inhibitor. 52% of low serum IGF-1 measurements were concurrent with a height percentile <5th.

Conclusions: Greater than expected percentages of patients had height/weight <5th percentile, and median final adult heights were

Impact statement: Children and adolescents/young adults with neurofibromatosis type I (NF1) seen at a research hospital have lower height and weight percentiles than normative populations. Growth percentiles are inversely associated with plexiform neurofibroma tumor volumes and impacted little by MEKi treatment history in this subset of patients. These findings align with prior investigations of growth in the NF1 population but are the first to examine the association with tumor burden.