A Prospective Randomised Phase III Clinical Trial Testing the Role of Prophylactic Cranial Radiotherapy in Patients...

A high incidence of central nervous system (CNS) metastases has been reported in patients with HER2-positive tumours receiving trastuzumab therapy for metastatic breast cancer. This study tested whether prophylactic cranial irradiation (PCI) could reduce the incidence of CNS metastases in this setting. This was a prospective, randomised phase III trial. Patients were randomised 1:1 to no PCI or PCI delivered at around 6 weeks after study entry. Cognitive function was assessed prospectively. In total, 51 patients were randomised over a 3 year period; 25 received PCI and 26 did not. The cumulative incidence of CNS metastases at 2 years was 32.4% (standard error = 9.8%) on the no PCI arm and 21.0% (standard error = 8.6%) on the PCI arm; the associated hazard ratio was 0.57 (95% confidence interval 0.18-1.74; P = 0.32). There was no evidence of cognitive dysfunction in PCI patients.