An International Expert Consensus Survey for A Treatment Versus Observation Strategy of Newly Diagnosed Patients with NF1 Associated Optic Pathway Glioma

Background/Objectives: Optic pathway glioma (OPG) develop in 15-20% of children with neurofibromatosis type 1 (NF-1), threatening vision loss but not survival. There is no consensus about the most appropriate strategy for selecting newly diagnosed patients with NF-1 for treatment or observation. Design/Methods: 25 representative case scenarios, derived from a risk-adapted matrix of newly diagnosed children with NF-1 OPG, previously entered the SIOP LGG 2004 trial, were used for a strategy selection consensus survey. The respondents were 98 multi-disciplinary specialists for the first survey (10 cases) and 46 for the second survey (15 cases) from an international multi-professional expert group. Respondents selected cases for initial observation (O) initial treatment (T) or randomisation between the two (R), justifying their selection with free text comments. A qualitative analysis of the free text comments describing reasoning was carried out by two reviewers and a mediator, following the grounded theory approach, allocating reasons to 8 themes, developed inductively. Results: Greater than 70% agreement between survey respondents occurred for initial observation in 4/25 cases, initial treatment in 10/25 cases, less than 70% consensus occurred in 11/25 cases. The associated 808 free text comments justifying selection for O: 173; T: 426 and R: 209 were allocated by 2 reviewers to 8 themes (agreement; k: 0.762). Consensus selection for: observation was justified by risk of progression (39%) and visual function (33%); for treatment by visual function (39%); for randomization by visual function (31%), risk of progression (22%), site/dimension of tumour (15%) and age and gender (12%). Conclusions: This survey and its qualitative analysis identifies a new consensus of justified criteria for initial observation versus treatment, in 11/25 scenarios no consensus was reached. These criteria are proposed as eligibility criteria for future trials where a randomised trial of indications for initial management could be included. on behalf of the SIOPE NF-1 OPG Nottingham, UK, Workshop (Participating centers: Berlin, Copenhagen, GOS, Hamburg, Leeds, Nottingham, Padua, Paris, Vienna)