What is known about tumour proliferation rates to choose between accelerated fractionation or hyperfractionation?

Repopulation of surviving clonogenic tumour cells during fractionated radiotherapy is one of the crucial factors determining cure probability in radiotherapy. Clinical and experimental data suggest that repopulation rates vary considerably between different tumours but may be similar to the cell production rates in the untreated tumour. For those tumours which repopulate fast, such as squamous cell carcinomas, bladder cancer and colorectal carcinomas, accelerated fractionation may be indicated.