Adult height after cranial irradiation for optic pathway tumors: relationship with neurofibromatosis.

Objective: Optic pathway tumors decrease adult height by central precocious puberty (PP) or hypothalamic-pituitary disorders, particularly growth hormone (GH) deficiency caused by the tumor, management of the tumor, or associated neurofibromatosis 1. The objective of this study was to evaluate the respective roles of these factors on disorders and adult height.

Study Design: Thirty-five patients with optic pathway tumors diagnosed at 6.4 +/- 0.6 years treated by cranial irradiation (30-56 Gy) reached adult height after treatment with GH alone (n = 16), gonadotropin hormone-releasing hormone analogue alone (n = 2), or both (n = 16).

Results: Central precocious puberty occurred before irradiation in four cases and after irradiation in 18. Eleven of the 17 patients with neurofibromatosis 1 had PP. Before irradiation, five of 21 patients lacked GH, zero of 21 lacked thyroid-stimulating hormone, and zero of 13 lacked adrenocorticotropin. After irradiation, 35 of 35 lacked GH, 28 of 35 lacked thyroid-stimulating hormone, and six of 35 lacked adrenocorticotropin; puberty was delayed in 15 patients. Adult height was -0.8 +/- 0.2 SD, below target height (0.2 +/- 0.2 SD, P <.0001), similar in patients with and without PP, but lower in those with neurofibromatosis 1 (-1.4 +/- 0.4 SD) than in those without (-0.3 +/- 0.3 SD, P =.04).

Conclusions: Optic pathway tumors cause PP, but cranial irradiation causes most of the other hypothalamic-pituitary disorders. Adult height of patients given GH or gonadotropin hormone-releasing hormone analogue seems to depend on neurofibromatosis 1.