Abstract Background For localized germinoma, whole-ventricular radiotherapy (WVRT) is standard-of-care in Europe; 24 Gray (Gy) with 16Gy boost following chemotherapy. The SIOP-CNS-GCT-II trial aimed to examine the effect of response-adapted radiotherapy on patient outcome. Methods Patients with localized germinoma received four courses of ‘carboPEI’ chemotherapy, then 24Gy WVRT if in complete remission (CR), with an additional 16Gy tumor boost if residual disease was present. Metastatic cases received 24Gy craniospinal radiotherapy (CSRT) with 16Gy boost to all sites. Results Between 2012 and 2018, 227 fully-staged germinoma patients were treated according to protocol. Five-year event-free (EFS) and overall survival (OS) for 166 localized germinoma were 0.94 ± 0.02 and 0.98 ± 0.01, respectively. Sixty-five of 166 (39.2%) were in CR after chemotherapy, of whom 64/65 received 24Gy WVRT, only two of whom (2/64; 3.1%) relapsed. Of 90/166 patients in partial remission (PR) after chemotherapy, 88/90 received 24Gy WVRT + 16Gy; two relapsed (2/88; 2.3%). Of the 11 remaining patients, eight had stable disease (SD) after chemotherapy; 7/8 received 24Gy WVRT + 16Gy boost and one 24Gy WVRT + 30Gy boost because of a teratoma component; none relapsed. Three remaining patients with progressive disease (PD) during chemotherapy had variable treatments, due to differing histologies and disease spread; one relapsed. Five-year EFS and OS for 61 metastatic germinoma were 0.98 ± 0.02 and 1.00 ± 0.00 respectively, with 55/61 (90.2%) in CR and 5/61 (11.5%) in PR after 24Gy CSRT + 16Gy; one relapsed. Conclusions Response-adapted radiotherapy for localized germinoma led to excellent survival outcomes. Further treatment de-escalation should be considered in future strategies to reduce treatment burden and late-effects.
Calaminus et al. (Mon,) studied this question.