Delayed adverse effects after irradiation of gliomas: clinicopathological analysis

Out of 107 pts. treated with radio- and chemotherapy for low and high grade gliomas (TD: 45-65Gy), 3 cases developed pathologically documented radionecrosis (coagulative necrosis with minimal or no persistent tumor). Clinico-therapeutic modalities were analyzed for all cases and biologically equivalent doses were calculated according to NSD, ED and btu formulas. All cases of radionecrosis fell into the group of doses close to 60Gy/30fx./42d. and NSD = 1758, ED = 1340 and btu = 1161. Isodose curve reconstruction on planes corresponding to histological sections of brains with radionecrosis demonstrated that doses received by areas of necrosis were higher than the calculated mid-plane doses in two cases. Clinical and autoptic incidence of radionecrosis were 2.8% and 10% respectively. High doses of steroids during RT seemed to offer some protection against radionecrosis, while number of chemotherapy cycles did not influence the risk of radionecrosis. A higher autoptic rate of irradiated gliomas is needed in order to obtain a better understanding of a number of unresolved problems.