APOPTOSIS: THE ROLE IN CANCER AND RADIOTHERAPY

Apoptosis has been defined as a process of programmed, active cell death, that is controlled by gene expression. In experimental studies, it has been shown that radiation, antineoplastic agents or hormonal deprivation may cause apoptotic cell death and this process has been regulated by genes such as p53, bcl-2, c-myc and the growth factors. Although, experimental studies have shown a positive correlation between the radiotherapy response and amount of spontaneous apoptosis, contradictory results have been observed in clinical studies. Because of these contradictory results, the role of apoptosis in radiation response and the prognosis is still unclear.