Ablative Radiotherapy of Brain Metastases and Postoperative Radiotherapy with or Without “Prophylactic” Cranial Irradiation Using Rapidarc and Simultaneous Integrated Boost (SIB)

ABSTRACT Objective Patients with solitary or few brain metastases and good performance status should be treated with a local radical intention. It remains unclear, whether additional whole brain radiotherapy WBRT is necessary. We report about our alternative radiotherapy procedure with fractionated radical dose to metastases and "mild" dose to the remaining brain. Materials and methods From 1/2010 until 12/2011 we treated 84 metastases in 46 patients with radical intent. 25 patients had a solitary lesion and 12 were irradiated after resection. Using RapidArc technique with simultaneous integrated boost (SIB) most metastases were treated to 15 × 4 Gy = 60 Gy (PTV1) and the whole brain received - if indicated- a "prophylactic" dose of 15 × 1.8 Gy = 27 Gy (PTV2) . 13 Patients received local treatment for their metastases without WBRT. Following resection of the metastasis the tumour bed was irradiated to 15 x 3.2 Gy = 48 Gy, residual/unresected macroscopic tumour to 15 x 4 Gy = 60 Gy. A 3-5 mm margin was used from GTV to PTV, with no additional margin for CTV. The minimum dose of PTV1 was 95% of the prescribed dose, wheras the median dose for PTV2 was 27 Gy. Results This treatment regime was tolerated very well without major toxicity and in general better than conventional WBRT (10 × 3 Gy). Median follow-up time after treatment was 7 months. 18 (39%) patients died and the median survival time is 12 months. Local tumour control after treatment with15x4 Gy has been 100%, whereas one metastasis relapsed after resection and postoperative RT (15 × 3.2 Gy). 10 patients (21%) were presented with new distant brain metastases. Conclusions Ablative treatment of brain metastases can be performed efficiently with RapidArc and combined with prophylactic cranial irradiation using SIB. Local tumor control is nearly 100% and the toxicity is very low. Disclosure All authors have declared no conflicts of interest.