Using Intensity Modulated Radiation Therapy (IMRT) for Brain Metastases

Traditionally, whole brain radiation therapy (WBRT) has been the primary therapy for patients with brain metastases. Despite this therapy, patients still have poor survival of four to six months. Untreated patients have a median survival of one month. Up to one half of these patients die of causes related to the presence of brain metastases. In a Phase I/II RTOG trial, the efficacy and safety of delivering accelerated fractionation was investigated in patients with good prognostic factors. No toxicity was observed with escalating dose of irradiation up 70.40Gy in 1.6Gy twice daily treatments. However, in a randomized trial, the use of hyperfractionation did not appear to improve survival when compared to 30Gy whole brain irradiation delivered in 10 fractions. Current therapeutic approach also includes stereotactic radiosurgery (SRS). Several retrospective studies have demonstrated improved local tumor control of 80% with addition of SRS to WBRT. These local control rates were comparable to surgery. In a recently published randomized trial by RTOG 95-08 (TJU accrued 42 patients to this trial), Andrews et al. demonstrated improved survival in patients with solitary brain lesion treated with SRS. Median survival was 6.5 months in patients treated with WBRT and SRS compared to 4.9 months in patients treated with WBRT alone. Also, these patients were more likely to have stable or improved performance status.