706P - Stereotactic radiosurgery (SRS) in brain metastases (BMs) from non-seminomatous germ cell tumours (NSCGTs)

Background

NSGCTs with BMs are deemed poor-risk by definition. The data on the use and clinical outcomes of SRS in this cohort of patients (pts) is limited.

Methods

This retrospective audit included all pts with BM from metastatic NSGCT treated with SRS at the Royal Marsden Hospital between 2016 and 2024. Pts were required to meet the commissioning criteria for SRS (controllable/absent extracranial disease, expected prognosis ≥6 months, Karnofsy Performance Status, KPS >70). All pts were discussed in specialist germ cell and SRS MDMs. All were treated using a CyberKnife system.

Results

Ten pts were treated. One received 2 and another 3 courses of SRS; total no. of treatments delivered was 13. Median (IQR) age at diagnosis: 31.5 (22-46) yrs. Median (range) time to SRS from diagnosis: 8 (4-205) mts. 2/10 had mediastinal GCT, 8/10 had testicular GCT. 4/10 had BMs on diagnosis. Median (range) KPS: 90 (70-100). Most common chemotherapy regimens: high-dose stem cell rescue (6/10), TIP (5/10), IPE (4/10), CBOP-BEP (4/10). SRS treatments were: alone (9/13), boost post whole brain radiotherapy, WBRT (2/13), to tumour bed alone post-surgery (2/13). 4/10 pts had WBRT: 3/4 prior to SRS of whom 2/3 received SRS boost, 1/3 received SRS on progression; 1/4 had WBRT after debulking surgery on progression after SRS. Most had 1 BM on planning MRI (6/13). Mean (range) GTV/CTV volume: 4.24 (0.07-15.42) cc. SRS doses: 24Gy/3# (4/13), 24Gy/1# (3/13), 21Gy/1# (3/13), 20Gy/1# (1/13), 18Gy/3# (1/13), 18Gy/1# (1/13). Survival was analysed from date of SRS. Median (range) follow-up: 17 (1-80) mts. There were six instances of intracranial progression in 4/10 pts, all failed extracranially. 7/10 pts progressed extracranially: 1/7 salvaged, 3/7 died, 3/7 are on chemotherapy. Intracranial control: 6/10 pts. Both intracranial and extracranial control: 3/10 pts. Median (95% CI) progression-free survival (PFS): 4 (3-5) months. Mean (95% CI) overall survival (OS): 56 (34-78) mts. Two-year OS and PFS were 67% and 23%. The presence of a mediastinal primary adversely impacted OS (Mantel-Cox P=0.005). Younger age (<40 yrs) or BM at diagnosis did not affect OS or PFS.

Conclusions

The use of SRS achieved durable intracranial control in BM in mNSGCT and is appropriate in carefully selected patients.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.