RBIO-05. THE IMPACT OF STEREOTATIC RADIOSURGERY (SRS) FOR THE RESIDUAL LESIONS OF PINEAL NON-GERMINOMATOUS GERM CELL TUMORS (NGGCTS) FOLLOWING CONVENTIONAL RADIOTHERAPY: A RETROSPECTIVE STUDY

Abstract

Abstract OBJECTIVE To evaluate the safety and efficacy of stereotatic radiosurgery (SRS) in treating residual lesions of pineal non-germinomatous germ cell tumors (NGGCTs) after conventional radiotherapy. METHODS The patients admitted to Guangdong Sanjiu Brain Hospital from 1 January 2008 to 31 December 2018 who diagnosed with pineal NGGCTs pathologically or clinically were retrospectively analyzed. Among those, the patients received conventional radiotherapy with or without SRS were included. The residual lesions after radiotherapy were defined with a maximum diameter > 10mm. Prognosis related parameters such as local control rate, progress-free survival, overall survival and treatment-related toxicity were determined. RESULTS The median follow-up time was 34 months (range 8-142 months). The objective response rate and disease control rate were 71.4% and 95.2%, respectively. Three-year progression-free survival rate was 85.2% and 3-year total survival rate was 88.0%. The univariate analysis revealed that both age and concurrent chemotherapy were not correlated with the prognosis (P=0.286, 0.824). Partial tumor resection before radiotherapy and chemotherapy, AFP >500ng/ml, and no more than 4 cycles of adjuvant chemotherapy were poor prognostic factors (P=0.037, 0.010, 0.006). Moreover, no acute radiation response was observed after treatment with SRS. Only 1 out of 27 patients (3.7%) had brain neurotoxicity related to a prolonged course of radiochemotherapy. CONCLUSION SRS for residual lesions of NGGCTs following conventional radiotherapy appears to be well tolerant and improved local control. However, the therapeutic efficacy of conventional radiotherapy combined with SRS warrants further investigations in a large-scale randomized controlled clinical trials.