Boost Irradiation Integrated to Whole Brain Radiotherapy in the Management of Brain Metastases

Abstract

Our retrospective analysis aimed to evaluate the clinical value of dose intensification schemes: WBRT and consecutive, delayed, or simultaneous integrated boost (SIB) in brain metastasis (BM) management. Clinical data and overall survival (OS) of 468 patients with BM from various primaries treated with 10 × 3 Gy WBRT (n = 195), WBRT+ 10 × 2 Gy boost (n = 125), or simultaneously 15 × 2.2 Gy WBRT+0.7 Gy boost (n = 148) during a 6-year period were statistically analysed. Significant difference in OS could be detected with additional boost to WBRT (3.3 versus 6.5 months) and this difference was confirmed for BMs of lung cancer and melanoma and both for oligo- and multiplex lesions. The OS was prolonged for the RPA 2 and RPA3 categories, if patients received escalated dose, 4.0 vs. 7.7 months; (p = 0.002) in class RPA2 and 2.6 vs. 4.2 months; (p < 0.0001) in the class RPA 3 respectively. The significant difference in OS was also achieved with SIB. The shortened overall treatment time of SIB with lower WBRT fraction dose exhibited survival benefit over WBRT alone, and could be applied for patients developing BM even with unfavourable prognostic factors. These results warrant for further study of this approach with dose escalation using the lately available solutions for hippocampus sparing and fractionated stereotactic irradiation. The simultaneous delivery of WBRT with reduced fraction dose and boost proved to be advantageous prolonging the OS with shortened treatment time and reduced probability for cognitive decline development even for patients with poor performance status and progressing extracranial disease.

Whole-Brain Radiation Therapy With Simultaneous Integrated Boost Versus Whole-Brain Radiation Therapy Plus Stereotactic Radiosurgery for the Treatment of Brain Metastasis From Lung Cancer

“…However, WBRT alone only extends the median survival time by up to 6 months (9,10). WBRT plus in-field radiotherapy boost is an effective strategy for improving the intracranial control rate (ICR) and selecting patients who could experience significant survival benefits (11)(12)(13)(14)(15)(16)(17). WBRT followed by SRS (WBRT + SRS) and WBRT combined with simultaneous integrated boost (SIB) are the two main boost schemes for BM.…”

“…A dosimetric study showed that WBRT combined with SIB (WBRT + SIB) could satisfy the target dose and protect the surrounding normal tissues such as the hippocampus (19). Several studies have also reported that WBRT + SIB significantly improves ICR and survival compared to WBRT alone (14,16,20). However, it is unclear whether WBRT + SIB can improve efficacy and reduce toxicity compared to WBRT + SRS.…”

<p>Whole-brain helical tomotherapy with integrated boost for brain metastases in patients with malignant melanoma – final results of the BRAIN-RT trial</p>

“…In the Australian cohort reported by Awad et al using VMAT to apply hippocampal avoidance WBRT to 30 Gy in 15 fractions and a SIB to 50 Gy to median two BM, the median OS was 9.4 months 26. In addition, in a recent analysis on radiation techniques in BM from various tumors, Dobi et al reported dose-escalated radiotherapy to be able to improve survival in patients with BM from MM from 3.2 months after WBRT only to 6.5 months after dose-escalated treatment 31. In accordance to those prior publications, the analysis of the imaging response in every individual BM in the standard versus experimental arm in our trial revealed the SIB in the experimental arm to result in a significantly improved local control of the individual BM.…”

Use of a head-tilting baseplate during volumetric-modulated arc therapy (VMAT) to better protect organs at risk in hippocampal sparing whole brain radiotherapy (HS-WBRT)

“…Several studies have shown that intensive treatment for metastatic lesions, including surgery and stereotactic radiosurgery (SRS), combined with WBRT might improve local control of oligo-brain metastases [23,24]. Dobi et al have reported that dose escalation to brain metastatic lesion can achieve better local control and survival, even among patients with extracranial metastasis [25]. To reduce the risk of cognitive decline and improve clinical outcomes, attempts have been made at adding simultaneous integrated boost (SIB) to HS-WBRT.…”