Patient characteristics and treatment parameters
| Variable | fSRS and immunotherapy | fSRS alone | P value |
| n=63 | n=66 | ||
| Sex (female/male) | 34/29 | 31/35 | 1.0 |
| Age (years) | 0.8 | ||
| Median | 57 | 56 | |
| Range | 25–75 | 22–79 | |
| KPS | 0.5 | ||
| Median | 80 | 80 | |
| <70 | 9 | 10 | |
| 70–80 | 24 | 28 | |
| 90–100 | 30 | 28 | |
| Histology | 0.7 | ||
| NSCLC | 27 | 29 | |
| Melanoma | 36 | 37 | |
| Presence of molecular mutations | 0.8 | ||
| BRAF | 16 | 19 | |
| EGFR | 4 | 5 | |
| ALK | 1 | 2 | |
| Brain metastases at diagnosis | 0.9 | ||
| No | 47 | 48 | |
| Yes | 16 | 18 | |
| Type of immunotherapy | |||
| Nivolumab | 47 | ||
| Pembrolizumab | 16 | ||
| Extracranial disease | 0.8 | ||
| Absent | 16 | 18 | |
| Stable | 30 | 32 | |
| Progressive | 17 | 16 | |
| Number of metastases | 0.6 | ||
| Single | 26 | 31 | |
| Multiple(2–4) | 37 | 35 | |
| DS-GPA | 0.3 | ||
| 0–1 | 12 | 17 | |
| 1.5–2.5 | 35 | 36 | |
| 3–4 | 16 | 13 | |
| Size of resection cavity | 0.3 | ||
| <3 cm | 24 | 22 | |
| ≥3 cm | 42 | 47 | |
| GTV (cm3) | 14.9 | 17.1 | 0.2 |
| Median/range | 3.2–41.9 | 2.4–51.2 | |
| CTV (cm3) | 23.2 | 25.5 | |
| Median/range | 5.5–47.1 | 3.9–59.3 | |
| PTV (cm3) | 28.0 | 30.8 | |
| Median/range | 7.4–53.1 | 5.6–64.6 | |
ALK, anaplastic lymphoma kinase; BRAF, v-raf murine sarcoma viral oncogene homolog B1; CTV, clinical target volume; DS-GPA, diagnosis-specific graded prognostic factors; EGFR, epidermal growth factor receptor; fSRS, fractionated (3×9 Gy) stereotactic radiosurgery; GTV, gross target volume; KPS, Karnofsky performance status; NSCLC, non-small-cell lung cancer; PTV, planning target volume.