The fate of irradiated tumor cells

Radiotherapy remains a key component of modern multimodal anticancer treatment approaches. Although most clinically relevant improvements in radiation oncology are based on optimized radiation technology, it now becomes obvious that biology-based approaches will further boost the efficacy of modern radiation oncology. Of relevance to this is the question of the ultimate fate of an irradiated cell and the mechanistic basis of the induced cell death or inactivation observed. Research bearing on this question is reported in this issue of Oncogene by Wendt et al. (2005), who show that the levels of p21CIP/WAF1 play a key role in determining whether an irradiated tumour cell is arrested in the G2 phase of the cell cycle, rather than apoptosing. The demonstration that caffeine treatment can abrogate this G2 arrest, and that the cells go on to die, has implications for overcoming treatment resistance imposed by radiation-induced upregulation of p21CIP/WAF1.