Intraventricular neurocytomas: a systematic review of stereotactic radiosurgery and fractionated conventional radiotherapy for residual or recurrent tumors.

To determine optimal treatment for recurrent or residual intraventricular neurocytomas (IVNs), a systematic review of PubMed and EMBASE was conducted comparing fractionated conventional radiotherapy (FCRT) versus stereotactic radiosurgery (SRS). Inclusion criteria included histological IVN documentation, at least 6 months of follow-up observation and described dose of FCRT or SRS administered. Descriptive statistical and Kaplan-Meier analyses were performed. The literature search yielded 451 articles. Sixteen studies met inclusion criteria. The local tumor control proportion was 93% and 88% in the SRS and FCRT subgroups, respectively. The relative risk (RR) of local recurrence was 0.57 less (95% CI: 0.21-1.57; log-rank p=0.85) and the RR of all-cause mortality was 0.23 less (95% CI: 0.05-1.05; log-rank p=0.22) in SRS subgroup compared to the FCRT subgroup but did not reach statistical significance. Recurrence was significantly associated with presence of histological atypia (log-rank p<0.001). Severe complications were lower in SRS subgroup (5.5% versus 7.5%, p=0.74); however, distant tumor recurrence was slightly lower in the FCRT subgroup (1.5% versus 5.5%, p=0.24). The role of SRS or FCRT in the management of residual or recurrent IVNs will continue to depend on the balance between the risks and benefits of SRS and FCRT until better quality data are available.