Failure Patterns Of Glioblastoma After Postoperative Chemoradiotherapy With Regard To The Subventricular Zone

BackgroundGlioblastoma(GBM)tumor stem cells and brain neural stem cells are thought to promote tumor progression and subventricular zone(SVZ)is the largest neural stem cell storage area in adult brain.ObjectiveWe examined whether GBM contacting SVZ affect recurrence patterns after postoperative chemoradiotherapy.Methods103 patients with primary GBM,treated at Shandong cancer Hospital and Institute between 2012 and 2016,were included.All patients underwent surgical resection followed by adjuvant radiotherapy and concomitant temozolomide.Preoperative images and follow-up examination results were assessed to evaluate tumor location.Tumors were categorized as SVZ contacting or non-contacting.The chi-square test was used to analyze the association between tumor contact and recurrence pattern.Kaplan-Meier survival curve was used to analyze PFS.Results40 of 103(38.8%)tumors were non-contacting SVZ and 63 of 103(61.2%)tumors were initially contacting SVZ at initial presentation.Of these,60 tumors(58.3%)were local recurrence and 43 tumors(41.7%)were distant metastases.67 tumors(65%)were found as multifocal recurrence and 36 replases(35%)as single lesion.Chi-square test showed that primary tumor contacting SVZ did not affect postoperative recurrence pattern.Kaplan-Meier survival curve showed no statistical difference in PFS between the two groups.However subgroup analysis showed that the primary lesion of non-contacting SVZ group had better progression free survival than the primary lesion contacting SVZ group in patients with complete resection of the primary tumor(P=0.036).For primary tumor non-contacting SVZ,27 of 40(67.5%)recurrence contacted SVZ.For the 43 patients with distant metastases,93 distant metastatic lesions were observed and 84/93(90.3%)lesions were distributed within 2 cm around SVZ.ConclusionAlthough initial location of tumor contacting SVZ did not change the relapse mode,we found that most of GBM distant metastases occurred in the SVZ around 2cm range in our study.GBM without SVZ infiltration showed increased PFS compared with infiltration in total resecting subgroup.