Cyberknife® hypofractionated stereotactic radiosurgery (CK-hSRS) as salvage treatment for brain metastases

J Cancer Res Clin Oncol. 2021 Sep;147(9):2765-2773. doi: 10.1007/s00432-021-03564-z. Epub 2021 Feb 26.

Abstract

Purpose: The introduction of hypofractionated stereotactic radiosurgery (hSRS) extended the treatment modalities beyond the well-established single-fraction stereotactic radiosurgery and fractionated radiotherapy. Here, we report the efficacy and side effects of hSRS using Cyberknife® (CK-hSRS) for the treatment of patients with critical brain metastases (BM) and a very poor prognosis. We discuss our experience in light of current literature.

Methods: All patients who underwent CK-hSRS over 3 years were retrospectively included. We applied a surface dose of 27 Gy in 3 fractions. Rates of local control (LC), systemic progression-free survival (PFS), and overall survival (OS) were estimated using Kaplan-Meier method. Treatment-related complications were rated using the Common Terminology Criteria for Adverse Events (CTCAE).

Results: We analyzed 34 patients with 75 BM. 53% of the patients had a large tumor, tumor location was eloquent in 32%, and deep seated in 15%. 36% of tumors were recurrent after previous irradiation. The median Karnofsky Performance Status was 65%. The actuarial rates of LC at 3, 6, and 12 months were 98%, 98%, and 78.6%, respectively. Three, 6, and 12 months PFS was 38%, 32%, and 15%, and OS was 65%, 47%, and 28%, respectively. Median OS was significantly associated with higher KPS, which was the only significant factor for survival. Complications CTCAE grade 1-3 were observed in 12%.

Conclusion: Our radiation schedule showed a reasonable treatment effectiveness and tolerance. Representing an optimal salvage treatment for critical BM in patients with a very poor prognosis and clinical performance state, CK-hSRS may close the gap between surgery, stereotactic radiosurgery, conventional radiotherapy, and palliative care.

Keywords: Brain metastasis; Cyberknife; Hypofractionated stereotactical radiosurgery; Neurooncology; Salvage treatment.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Neoplasms / secondary
  • Brain Neoplasms / surgery*
  • Female
  • Follow-Up Studies
  • Humans
  • Karnofsky Performance Status
  • Male
  • Middle Aged
  • Neoplasms / pathology
  • Neoplasms / surgery*
  • Radiation Dose Hypofractionation
  • Radiosurgery / mortality*
  • Retrospective Studies
  • Salvage Therapy / mortality*
  • Survival Rate
  • Treatment Outcome