No date

Session Item

Sunday

August 29

16:45 - 17:45

Room 1

Proffered papers 25: Upper GI

Chair: , Belgium;

Chair: , Austria

Session Type: Proffered papers

Track: Clinical

Journey:

10:30 - 10:40

Reirradiation of brain metastases with SRS after local or marginal recurrence from prior SRS

Roman Kowalchuk, USA

Presentation Number: OC-0073

Abstract

Abstract Title:

Reirradiation of brain metastases with SRS after local or marginal recurrence from prior SRS

Authors:

Roman Kowalchuk¹, Ajay Niranjan², Cheng-chia Lee³, Huai-che Yang³, Roman Liscak⁴, Khumar Guseynova⁴, Manjul Tripathi⁵, Narenda Kumar⁶, Selcuk Peker⁷, Yavuz Samanci⁷, Judith Hess⁸, Veronica Chang⁸, Christian Iorio-Morin⁹, David Mathieu⁹, Stylianos Pikis¹⁰, Zhishuo Wei², L Lunsford², Daniel Trifiletti¹¹, Jason Sheehan¹⁰

¹Mayo Clinic, Radiation Oncology, Rochester, USA; ²University of Pittsburgh, Neurological Surgery, Pittsburgh, USA; ³Neurological Institute, Taipei Veteran General Hospital, Neurosurgery, Taipei, Taiwan; ⁴Na Homolce Hospital, Stereotactic and radiation neurosurgery, Prague, Czech Republic; ⁵Postgraduate Institute of Medical Education and Research, Neurosurgery, Chandigarh, India; ⁶Postgraduate Institute of Medical Education and Research, Radiotherapy, Chandigarh, India; ⁷Koc University School of Medicine, Neurosurgery, Istanbul, Turkey; ⁸Yale, Neurosurgery, New Haven, USA; ⁹Université de Sherbrooke, Neurosurgery, Quebec, Canada; ¹⁰University of Virginia, Neurosurgery, Charlottesville, USA; ¹¹Mayo Clinic, Radiation Oncology, Jacksonville, USA

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Purpose or Objective

Brain metastases represent a major indication for stereotactic radiosurgery (SRS), and while there is evidence demonstrating efficacy of SRS after whole brain radiotherapy (WBRT), there is a paucity of literature regarding its role after local or marginal recurrence of a brain metastasis previously treated with SRS. We report local tumor control (LC) and radiation necrosis (RN) rates after the second SRS procedure, and we identify predictors of RN and symptomatic RN (SRN).

Material and Methods

An international, multi-institutional study was performed under the auspices of the International Radiosurgery Research Foundation. We included patients with biopsy-proven non-small cell lung cancer with at least one brain metastasis status-post treatment with SRS. Repeat SRS (SRS2) was performed from 2015 through 2019 after local or marginal recurrence following initial SRS (SRS1). Patients receiving SRS after only WBRT or those treated with preoperative SRS were excluded. The primary endpoints were LC by RANO criteria, RN, and SRN.

Results

A set of 154 lesions treated in 124 unique patients was assembled from 8 institutions, with 134 treatments included in the final outcomes analysis. 41 treatments involved prior immunotherapy use, and SRS1 occurred a median 12 months prior to SRS2. SRS1 involved delivery of a median 18 Gy (10-27) margin dose to the 55% (35-96) isodose line, with a maximum dose of 32.2 Gy (0.7-67.5) and a V12Gy of 3.94 cc (0.05-110.37). SRS2 had a median 18 Gy (10.5-30) margin dose to the 50% (19-96) isodose line, with a maximum dose of 32 Gy (16.2-85) and a V12 of 3.31 cc (0.02-71.3). At a median 15 months of follow-up after SRS2, 23.9% of lesions had progressed, with 1-year and 2-year LC of 78.9% and 71.6%. LC was reduced with tumor volume > 1 cc on SRS2 (p=0.01). RN occurred after 28 (20.9%) treatments, with 10 (7.5%) cases of SRN. Increasing values of SRS1 maximum dose, SRS2 maximum dose, SRS1 V12, and SRS2 V12 correlated with increasing rates of SRN and RN. Maximum doses ≥ 40 Gy in SRS1 and SRS2 resulted in SRN rates of 16% and 21%, compared to 3.8% and 6.5% with maximum does ≤ 30 Gy (Figure 1).

Similarly, V12 > 9 cc in SRS1 and SRS2 resulted in SRN rates of 12.5% and 17.2%, compared to 7.1% and 4.2% with V12 ≤ 5 cc (Figure 2).

Prior immunotherapy was not predictive of RN or SRN. At last follow-up, intracranial disease progression was noted after 45.5% of treatments. Additional radiotherapy (24.6%) and surgery (13.4%) were often utilized in these cases.

Conclusion

We present a large, multi-institutional cohort of brain metastases treated with SRS after local or marginal failure following prior SRS. Repeat SRS generally afforded a high rate of local tumor control and a low rate of SRN. Maximum dose and V12 are predictive factors for RN. Lower V12 and maximum dose may reduce the risk of SRN, but these should not be reduced at the expense of delivering a therapeutic dose to achieve local tumor control.