Rapid repopulation in radiotherapy: a debate on mechanism. Accelerated repopulation in tumours and normal tissues.

Accelerated repopulation is a well established response pattern of normal epithelial to fractionated irradiation. It is delayed until the tissue recognises functional injury. It is well regulated to maintain a steady state and continues until integrity of the tissue is restored. We assume that some of these features of the parental normal tissue are preserved and still operate in squamous cell carcinoma, although probably in a less well controlled and organised manner.