Whole ventricular radiotherapy (WVRT) at a dose of 24 Gy is sufficient to maintain complete remission (CR) in patients with localized germinoma, according to research presented at the 20th International Symposium on Pediatric Neuro-Oncology (ISPNO).
These results come from the SIOP CNS GCT II trial (ClinicalTrials.gov Identifier: NCT01424839), which included 166 patients with localized germinoma. There were 91 patients with pineal tumors, 45 with suprasellar tumors, and 30 with bifocal tumors.
All patients had received chemotherapy consisting of carboplatin, etoposide, and ifosfamide. Those patients who achieved a CR after chemotherapy (n=65) received 24 Gy of WVRT alone.
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Patients who had achieved partial remission (PR; n=90) received 24 Gy of WVRT with a 16 Gy boost. Patients with stable disease (SD; n=8) or progressive disease (PD; n=3) underwent resection and/or received additional chemotherapy, followed by 24 Gy of WVRT with a 30 Gy boost.
The median follow-up was 4.2 years. Of the 65 patients who achieved a CR with chemotherapy, 63 remained in CR after WVRT and at the final follow-up. For the 2 patients who relapsed, 1 achieved a second CR and the other died.
Of the 90 patients in the PR cohort, 85 achieved a CR after WVRT, and 84 maintained a CR at the final follow-up. The patient who was not in CR at last follow-up had died of an infection while in CR. Among the 5 patients who relapsed after radiotherapy, 4 achieved a second CR at the final follow-up, and 1 patient had a second relapse.
Of the 8 patients with SD, all achieved a CR after WVRT and maintained their response at the final follow-up. Of the 3 patients with PD, 2 achieved a CR after WVRT and maintained their response at the final follow-up. The patient who had relapsed after radiotherapy achieved a second CR.
The 4-year event-free survival rate was 97% for patients in CR who received WVRT alone and 95% for patients who were not in CR and received WVRT with tumor boost (P =.61).
These results suggest that patients with localized germinoma who have a CR after chemotherapy can be safely treated with WVRT alone, said study presenter Gabriele Calaminus, MD, of University Children’s Hospital in Bonn, Germany.
She added that this defines a new therapeutic standard for about 80% of patients with localized germinoma. In cases of relapse, additional chemotherapy and radiation can produce a second CR in most patients.
In the future, Dr Calaminus and colleagues plan to investigate whether an additional reduction to 21 Gy can maintain durable CR after chemotherapy in localized germinoma and whether a reduction in craniospinal irradiation and tumor boost is feasible for patients with metastatic disease.
Reference
Calaminus G, Bison B, Conter CF, et al. 24 Gy whole ventricular radiotherapy alone is sufficient for disease control in localised germinoma in CR after initial chemotherapy – final of the SIOP CNS GCT II study. Presented at ISPNO 2022; June 12-15, 2022. Abstract GCT-11.
