R8.7: Factors Determining Tumour Regression Rate

Tumour regression is the shrinking of tumours following administration of radiation. To determine tumour regression, the size of a treated and untreated (control) tumour are taken at a specific time point and compared, giving the T/C ratio.
There are numerous factors which influence the T/C ratio. These include the ratio of malignant to non-malignant cells in the tumour, oedema of the tissue, clearance of dead cells and proliferation of neighbouring tissues.
Due to the number of factors involved in tumour regression, it is fairly non-specific and is of limited value.