Distance between brain metastases of non-small cell lung cancer and the hippocampus and its correlation with PTV low-dose regions in prophylactic cranial irradiation with hippocampal avoidance: an analysis of 56 patients / 中华放射肿瘤学杂志

ABSTRACT

Objective To investigate the feasibility of prophylactic cranial irradiation with hippocampal avoidance (HA-PCI) in non-small cell lung cancer (NSCLC).Methods The clinical data of 56 patients with brain metastases of NSCLC who were treated from 2011 to 2014 were collected.Brain metastases and the hippocampus were delineated on T1 W1 contrast-enhanced MRI,and the distance between brain metastases and the hippocampus was analyzed;an HA-PCI regimen was also developed,and the distribution of the metastases in planning target volume (PTV) low-dose regions around the hippocampus was analyzed.Results None of the 139 metastases involved the hippocampus.There were 6(4.3％) and 18 (12.9％) metastases within 5 mm and 10 mm,respectively,outside the hippocampus.In the HA-PCI regimen,the D50％ and D2％ of PTV were 25.6 Gy and 27.1 Gy,respectively.Dmean and D2％ for the hippocampus were 7.4 Gy and 9.9 Gy,respectively;D50％ within 0-5.0 mm,5.1-10.0 mm,and 10.1-15.0 mm outside the hippocampus was 10.3 Gy,15.1 Gy,and 20.5 Gy,respectively.Conclusions HA-PCI may be feasible theoretically,but this needs to be confirmed by the intracranial failure pattern in patients with long-term survival.