Our present results of NSCLC and data from papillary bladder carcinoma (Krueger et al, unpublished), as well as breast cancer (Maacke et al, 2000b) and pancreatic cancer (Maacke et al, 2000a; Han et al, 2002) strongly suggest that high-level Rad51 expression might be a permissive event for tumour progression, probably because it helps to keep DNA damage at a tolerable level for cell survival and at the same time enhancing genetic instability. Here, RAD51 is linked to breast cancer.