Radiation induced brachial plexopathies

A daily challenge for the radiation oncologist is toprescribe the optimal radiation dose that will pro-duce the maximal probability of local tumour con-trol, and, at the same time, minimal risk forcomplications. The radiation dose needed to controltumours is commonly close to that tolerated bynormal tissues. Thus, the level of normal tissuemorbidity will often determine the cure rate that maybe achieved.Both tumour cure and serious normal tissuedamage depend on the extent of cell depopulation.Every clonogenic stem cell has to be killed in thetumour to achieve long lasting tumour control.Clonogenic cells, however, have to survive in normaltissues to avoid serious normal tissue damage.Tolerance doses are not absolute values and theyare different for different tissues.The tolerance dose depends on various biological(patient-related) and treatment-related factors. Topatient-related factors belong e.g. age and obesity.Obesity can affect the development of lymph-oedema [1,2]. Co-morbidities like diabetes, hyper-tension, or collagen vascular diseases [3,4] will alsoinfluence the normal tissue reactions. Treatment-related factors are, e.g. chemotherapy, surgery,radiation quality, irradiated volume, number andsize of fractions and overall treatment time [5].This gives a very complex picture that needs tobe individually assessed before prescribing thetreatment.The time of expression of the cellular injury afterirradiation is variable from one tissue to another.The severe acute reactions in rapidly proliferatingtissues can readily be observed and may thus rapidlyresult in changes in radiotherapy schedules that maybe ‘too hot’. This is not the case for late injuries thatcan occur long after completion of therapy. Latereactions are often defined as side effects that occurafter a latency period of more than six months. Theyare generally caused by depletion of slowly prolifer-ating cells with a slow rate of cell loss and renewal,e.g. in central or peripheral (Schwann cells) nervoustissue [6,7], blood vessels (endothelium) [8,9],dermis (fibroblasts) [10