Whole brain radiotherapy with adjuvant or concomitant boost in brain metastasis: dosimetric comparison between helical and volumetric IMRT technique.

BACKGROUND: To compare and evaluate the possible advantages related to the use of VMAT and helical IMRT and two different modalities of boost delivering, adjuvant stereotactic boost (SRS) or simultaneous integrated boost (SIB), in the treatment of brain metastasis (BM) in RPA classes I-II patients. METHODS: Ten patients were treated with helical IMRT, 5 of them with SRS after whole brain radiotherapy (WBRT) and 5 with SIB. MRI co-registration with planning CT was mandatory and prescribed doses were 30 Gy in 10 fractions (fr) for WBRT and 15Gy/1fr or 45Gy/10fr in SRS or SIB, respectively. For each patient, 4 "treatment plans" (VMAT SRS and SIB, helical IMRT SRS and SIB) were calculated and accepted if PTV boost was included in 95 % isodose and dose constraints of the main organs at risk were respected without major deviations. Homogeneity Index (HI), Conformal Index (CI) and Conformal Number (CN) were considered to compare the different plans. Moreover, time of treatment delivery was calculated and considered in the analysis. RESULTS: Volume of brain metastasis ranged between 1.43 and 51.01 cc (mean 12.89 ± 6.37 ml) and 3 patients had double lesions. V95% resulted over 95 % in the average for each kind of technique, but the "target coverage" was inadequate for VMAT planning with two sites. The HI resulted close to the ideal value of zero in all cases; VMAT-SIB, VMAT-SRS, Helical IMRT-SIB and Helical IMRT-SRS showed mean CI of 2.15, 2.10, 2.44 and 1.66, respectively (optimal range: 1.5-2.0). Helical IMRT-SRS was related to the best and reliable finding of CN (0.66). The mean of treatment time was 210 s, 467 s, 440 s, 1598 s, respectively, for VMAT-SIB, VMAT-SRS, Helical IMRT-SIB and Helical IMRT-SRS. CONCLUSIONS: This dosimetric comparison show that helical IMRT obtain better target coverage and respect of CI and CN; VMAT could be acceptable in solitary metastasis. SIB modality can be considered as a good choice for clinical and logistic compliance; literature's preliminary data are confirming also a radiobiological benefit for SIB. Helical IMRT-SRS seems less effective for the long time of treatment compared to other techniques.

The treatment of patients with 1-3 brain metastases: is there a place for whole brain radiotherapy alone, yet? A retrospective analysis.

AIM: To evaluate the efficacy of whole brain radiotherapy (WBRT) with or without other treatments in patients (pts) with 1-3 brain metastases (BM). MATERIALS AND METHODS: Toxicities and survival of 134 pts treated between 2009 and 2013 with WBRT alone (58 pts), WBRT plus surgery (SUR-WBRT: 42 pts) or WBRT followed by stereotactic or integrated boost radiotherapy (SRT-WBRT: 34 pts) were analyzed. Differences in toxicity (acute and late) incidence and in overall (OS), disease-free (DFS) and disease-specific survival (DSS) were evaluated (χ(2)-test, uni- and multivariate analysis). RESULTS: Pts given intensified treatments (SUR- and SBRT-WBRT) had better 3-month local response compared to WBRT alone group (p < 0.045). Better 1-year local control was evident only in SRT-WBRT pts (p < 0.035). Univariate OS analysis confirmed, as favorable prognostic factors, RPA class I (p < 0.001), GPA class III and IV (p < 0.001), single metastasis (p = 0.045), stable primary disease (p = 0.03), intensified treatment (p = 0.000), systemic therapy after radiotherapy (p = 0.04) and response of metastatic lesions (p = 0.002). At multivariate analysis, OS was better in RPA class I pts (p = 0.002), who had more aggressive radiotherapy treatments (p = 0.001), chemotherapy after radiotherapy (p < 0.001) and response to RT (p = 0.003). Response to radiotherapy (p = 0.002) and BM number (p < 0.001) resulted independently prognostic for DFS. About 60 % of patients had mild acute toxicity (G1), especially headache (51 %) and fatigue (34 %); only 2 patients (2 %) had severe (G3) headache and 5 patients (4 %) severe fatigue (G3) reversible with oral steroids. No differences were evident between the different treatment groups. Among 80 pts followed up with MRI, 12 (15 %) had leukoencephalopathy (equally distributed across subgroups) and 5 (6 %) radionecroses, 4/5 asymptomatic, 5/5 in pts given intensified treatments. CONCLUSIONS: This analysis confirms the known prognostic factors for BM, emphasizing the importance of intensified treatments in a population with favorable features.