Reirradiation for diffuse intrinsic pontine glioma: a systematic review and meta-analysis

Background: Diffuse intrinsic pontine glioma (DIPG) is a pediatric brain tumor with dismal prognosis despite initial radiation therapy (RT). The clinical consequences of attempting reirradiation (reRT) in these patients to alleviate both symptomatology and improve prognosis are currently unclear. Thus, the aim of this systematic review and meta-analysis was to clarify the efficacy and safety of reRT in DIPG. Methods: Searches of seven electronic databases from inception to January 2019 were conducted following the appropriate guidelines. Articles were screened against prespecified criteria. The incidence and duration of clinical outcomes were then extracted and pooled by means of meta-analysis from the included studies. Results: A total of 7 studies satisfied all criteria, describing 90 cases of DIPG in which reRT was attempted 11.8–14 months after initial RT. Based on a random-effects model, the incidences of clinical improvement and radiologic response following reRT were 87% (95% CI, 78–95%) and 69% (95% CI, 52–84%), respectively. The incidence of acute serious toxicity was 0% (95% CI, 0–4%). Pooled overall survivals from initial diagnosis and time of reRT were 18.0 months (95% CI, 14.2–21.7) and 6.2 months (95% CI, 5.5–7.0), respectively. Conclusions: Based on these results, the clinical consequences of reRT for DIPG when administered appropriately and safely at first progression appear acceptable, and potentially favorable, based on the limited evidence in the current literature. Concerns regarding acute serious toxicity were not realized. It is likely that a subcohort of all DIPG diagnoses will be most amenable to improve prognosis with reRT, and greater investigation is required to identify their characteristics.