ABSTRACT
There is no doubt that disruption of apoptosis plays a prominent role in the
development of cancer and the progression of the malignant phenotype. Indeed it
is widely accepted that evasion of apoptosis is one of the “hallmarks of cancer”
(1). There is also no doubt that apoptosis, and proteins involved in this complex
process, can convey prognostic information in a variety of different cancers
(2-9). There is also no doubt that apoptosis can be invoked by DNA-damaging
agents including radiation and chemotherapeutic drugs. However there is
considerable doubt whether apoptosis plays a central role in determining the
sensitivity of solid tumors to cancer therapy and particularly radiotherapy (RT)
(10-12). In this Chapter we will reveal what the clinical data has told us about
the significance of apoptosis in determining both the response and clinical
outcome of patients treated with cytotoxic therapy. The data will show us that the
picture is clear, i.e., there is no clear picture. The clinical literature surrounding
apoptosis is plagued by contradictory results and underpowered studies with
arbitrary cutoffs, ill-defined patients groups, and overinterpretation of the
data. However, there are many well-conducted studies that cast doubt on the
significance of apoptosis, or its related proteins, as determinants of cancer
therapy in solid tumors.
