Redefining Ventricular Target Volume in Germinoma: Is Inclusion of Temporal Horns Necessary?

PURPOSE: We reviewed the outcomes of a retrospective germinoma cohort and analyzed radiation therapy plans to determine dosimetric differences for critical structures. METHODS AND MATERIALS: Data from pediatric patients treated with photon radiation for intracranial germinoma were analyzed for clinical outcomes and dosimetry to critical structures, with particular interest in the temporal ventricular horns (TVHs). A consensus contour was generated for TVH-sparing ventricular clinical target volumes (CTVs) via deformable image registration. RESULTS: Twelve and 10 patients had their TVHs included or excluded in their ventricular CTVs, respectively. All patients were living at the time of analysis. One patient relapsed in the fourth ventricle, which had been omitted from the radiation therapy field. Mean dose was significantly lower to the hippocampi (Δ = -578 cGy, P = .0016) and temporal lobes (Δ = -599 cGy, P = .0007) in the TVH-excluded cohort compared with those with TVHs included in the treatment field. CONCLUSIONS: Exclusion of the TVHs from the CTV results in significant dose sparing to the hippocampi and temporal lobes. Clinical outcomes remain excellent with no deaths and no TVH failures. Exclusion of TVHs from the ventricular CTV in germinoma requires prospective study.