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Analysis of PN growth rates during adolescence in NF1

Monday, October 24, 2011 — Poster Session I

Noon – 2:00 p.m.

Natcher Conference Center




  • J Sabo
  • A Gillespie
  • W Goodspeed
  • A Goodwin
  • A Baldwin
  • J Solomon
  • S Steinberg
  • B Widemann
  • E Dombi


Background: Patients with neurofibromatosis type 1 (NF1) develop plexiform neurofibromas (PNs). We previously described that PNs grow more rapidly in younger patients compared to older patients. Objective: To analyze tumor growth rates in patients with NF1 to determine if growth rate changes occur during adolescence. Methods: PN volume was determined by volumetric MRI. Linear regression analysis was performed to assess the slope of PN growth for each patient. In peripubertal patients separate slopes were generated before and after the presumed onset of puberty. We performed paired analyses between the slopes associated with the younger vs. the older age, using a two-tailed Wilcoxon signed rank test to determine whether the slopes differed by age. Results: The slope of growth before and after the onset of puberty was available for 16 patients. The median slope of growth before age 9: 21 (range 0.1-51.7), after age 9: 16.2 (range -2.4-97.7) with p=0.90 for a paired comparison. The median slope of growth before age 11: 17.05 (1.4-60), after age 11: 13.6 (range -9.7-85.1) with p=0.98. Conclusion: While PN growth rates vary among patients, our preliminary data does not demonstrate increase in PN growth during adolescence. We will continue to follow patients into adulthood.

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