CENTRAL NERVOUS SYSTEM (CNS) RELAPSES AND PROGNOSTIC FACTORS AFFECTING THE RELAPSES: EVALUATION OF PATIENTS WITH ACUTE LYMPHOBLASTIC LEUKEMIA WHO RECEIVED 1800 CGY AND 2400 CGY CRANIAL RADIOTHERAPY (RT) FOR CNS PROPHYLAXIS

Between January 1982 and January 1993, 186 cases with acute lymphoblastic leukemia, who received cranial radiotherapy (RT) for central nervous system (CNS) prophylaxis were evaluated retrospectively. The range of their ages was 2-15 (median 5 years); 108 of them were male and 78 were female; 71 had favorable prognosis and 115 had unfavorable prognosis; 127 patients received 1800 cGy, 59 received 2400 cGy cranial RT. Among the whole group CNS relapse occurred in 16 cases (8.6%). This relapse rate was 10.1% for the 2400 cGy -cranial RT group and 7.8% for the 1800 cGy- cranial RT group. The groups were compared by X2 test and no statistically significant difference found between them (p=0.603). Three and 5 year survival rates without CNS relapse were 90.2% and 87.1% respectively. These survival rates showed no significant difference when compared according to radiotherapy doses (p=0.598), 3 different chemotherapy regimens (p=0.948), sex (p=0.548) and age groups (p=0.948). However the difference was significant among the risk groups (p=0.003). Likewise, with multivariate analysis, no statistically significant difference was found according to radiotherapy doses (p=0.704), 3 different chemotherapy regimens (p=0.475), sex (p=0.565) and age groups (p=0.478) whereas the difference between the favorable and unfavorable prognostic groups were statistically significant (p=0.007).