The Effect of Dose-Volume Parameters on Central Nervous System Relapse in Pediatric Patients with Acute Leukemia Receiving Prophylactic Cranial Irradiation.

Aim Of The Study: To investigate the effects of dosevolume parameters of brain parenchyma, optic nerves (ONs) and cribriform plate (CP), which were determined on central nervous system (CNS) control in pediatric leukemia patients who have undergone prophylactic cranial irradiation (PCI) at our department.

Patients And Methods: In the current study, the records of 14 patients were examined retrospectively. Along with the minimum and maximum doses for brain and CP, D95% (minimal dose received by the 95% volume of a structure) and V95% (percent volume of target receiving 95% of prescribed dose) could be obtained from the dose-volume histogram. Statistical analyses were conducted using the Mann Whitney test in SPSS-15.

Results: ALL/AML ratio was 9/5. CNS relapse was observed only in 2 patients. The minimum dose was 1249 (1100-1782) cGy, 1036 (547-1651) cGy, 856 (308-1460) cGy and 1234 (922-1727) cGy for brain parenchyma, right ON, left ON and CP, respectively. The value of D95%/D was 1.01 (1-1.06) and 0.99 (0.92- 1.06) for brain parenchyma and CP, respectively. V95% was 99.8 % (98.6%-100%) and 98.1% (80.5%-100%) for brain parenchyma and CP, respectively. The analyses revealed that none of the target tissue dose-volume parameters for PCI affected CNS relapse (p>0.05).

Conclusion: In our study; it was found that the dosevolume parameters of the brain, CP and ONs did not have any effect on CNS relapse. Along with the other clinical factors, the scarce number of patients included in the study might have concealed the effects of parameters related to RT.