Radiation Therapy for Brain Metasases

Abstract

Objective. This evidence report synthesizes the available evidence on radiation therapy for brain metastases. Data sources. We searched PubMed®, Embase®, Web of Science, Scopus, CINAHL®, clinicaltrials.gov, and published guidelines in July 2020; assessed independently submitted data; consulted with experts; and contacted authors. Review methods. The protocol was informed by Key Informants. The systematic review was supported by a Technical Expert Panel and is registered in PROSPERO (CRD42020168260). Two reviewers independently screened citations; data were abstracted by one reviewer and checked by an experienced reviewer. We included randomized controlled trials (RCTs) and large observational studies (for safety assessments), evaluating whole brain radiation therapy (WBRT) and stereotactic radiosurgery (SRS) alone or in combination, as initial or postoperative treatment, with or without systemic therapy for adults with brain metastases due to non-small cell lung cancer, breast cancer, or melanoma. Results. In total, 97 studies, reported in 190 publications, were identified, but the number of analyses was limited due to different intervention and comparator combinations as well as insufficient reporting of outcome data. Risk of bias varied; 25 trials were terminated early, predominantly due to poor accrual. Most studies evaluated WBRT, alone or in combination with SRS, as initial treatment; 10 RCTs reported on post-surgical interventions. The combination treatment SRS plus WBRT compared to SRS alone or WBRT alone showed no statistically significant difference in overall survival (hazard ratio [HR], 1.09; confidence interval [CI], 0.69 to 1.73; 4 RCTs; low strength of evidence [SoE]) or death due to brain metastases (relative risk [RR], 0.93; CI, 0.48 to 1.81; 3 RCTs; low SoE). Radiation therapy after surgery did not improve overall survival compared with surgery alone (HR, 0.98; CI, 0.76 to 1.26; 5 RCTs; moderate SoE). Data for quality of life, functional status, and cognitive effects were insufficient to determine effects of WBRT, SRS, or post-surgical interventions. We did not find systematic differences across interventions in serious adverse events radiation necrosis, fatigue, or seizures (all low or moderate SoE). WBRT plus systemic therapy (RR, 1.44; CI, 1.03 to 2.00; 14 studies; moderate SoE) was associated with increased risks for vomiting compared to WBRT alone. Conclusion. Despite the substantial research literature on radiation therapy, comparative effectiveness information is limited. There is a need for more data on patient-relevant outcomes such as quality of life, functional status, and cognitive effects.