SUMMARY: Brain metastases from an extracranial primary, occur in approximately 15% of cancer patients and this is estimated to be about 400,000 to 600,000 patients annually. The incidence of brain metastases has been on the rise with the availability of more effective systemic therapies and better control of systemic disease. The most frequent malignancies associated with brain metastases include Lung cancer, Breast cancer and Melanoma. Majority of the patients with brain metastases have synchronous extracerebral metastases. A significant number of patients present with solitary or fewer than 3 brain metastases and they may be amenable to focal therapeutic interventions. However, Whole Brain Radiation Therapy (WBRT) has been the standard treatment strategy since the 1950’s. It is also well recognized that WBRT can be associated with neurocognitive dysfunction. Stereotactic RadioSurgery (SRS) is a non-surgical procedure that allows delivery of significantly higher doses of precisely focused radiation to the tumor, compared to conventional radiation therapy, with less collateral damage to the surrounding normal tissue. The technologies used for SRS include GAMMA KNIFE® which uses highly focused gamma rays, Proton Beam therapy which uses ionized hydrogen or Protons, Linear Accelerator and CYBER KNIFE® which use Photons, to target the tumor tissue.
NCCTG N0574 is a federally funded, randomized phase III clinical trial, designed to determine whether cognitive deterioration occurred less frequently with SRS alone compared to SRS followed by WBRT, in patients with 1-3 brain metastases. In this study, 213 patients with 1-3 brain metastases, each measuring less than 3 cm by contrast MRI, were enrolled and randomized to SRS alone or SRS plus WBRT. All patients underwent cognitive testing before and after treatment. Sixty eight percent (68%) of the enrolled patients had a Lung primary and the median age was 60 years. Baseline characteristics were similar in both treatment groups. The median follow up was 7.2 months. The authors used several tools to assess cognitive dysfunction and the primary endpoint was the cognitive decline at 3 months following treatment. It was noted that at 3 months, with the addition of WBRT to SRS, 91.7% of patients experienced cognitive decline compared with 63.5% for those receiving SRS alone (P=0.0007) and there was statistically significant decline in immediate recall, delayed recall and verbal fluency, in the SRS plus WBRT group. Patients who received SRS plus WBRT also reported significantly worse Quality of Life. There was however better intracranial tumor control at 6 and 12 months with SRS plus WBRT compared to SRS alone (P< 0.001), but this local control had no significant impact on the median Overall Survival (OS), with similar OS outcomes noted in both treatment groups (P=0.93). The authors concluded that the addition of WBRT to SRS can result in significant decline in neurocognitive function, without any Overall Survival benefit, compared to SRS alone. It is therefore recommended that patients with newly diagnosed brain metastases amenable to SRS, be closely monitored after SRS, with consideration given to WBRT, at the time of symptomatic progression. NCCTG N0574 (Alliance): A phase III randomized trial of whole brain radiation therapy (WBRT) in addition to radiosurgery (SRS) in patients with 1 to 3 brain metastases. Brown PD, Asher AL, Ballman KV, et al. J Clin Oncol 33, 2015 (suppl; abstr LBA4)