RAD51 and neoplasm: Interestingly, in line with our in vitro results, comparison of progression-free survival (PFS) in patients of group 1 (low basal expression of RAD51 in GSCs) and group 2 (high basal expression of RAD51 in GSCs) revealed a better outcome for patients of group 1 (PFS ≥6 months in group 1 and PFS <6 months in group 2) (Additional file 3: Table S3 and Additional file 6: Figure S3), suggesting a potential involvement of RAD51 in tumor radioresistance.