A new grading system focusing on neurological outcomes for brain metastases treated with stereotactic radiosurgery: the modified Basic Score for Brain Metastases

Abstract

ObjectThe Basic Score for Brain Metastases (BSBM) proposed by Lorenzoni and colleagues is one of the best grading systems for predicting survival periods after stereotactic radiosurgery (SRS) for brain metastases. However, it includes no brain factors and cannot predict neurological outcomes, such as preservation of neurological function and prevention of neurological death. Herein, the authors propose a modified BSBM, adding 4 brain factors to the original BSBM, enabling prediction of neurological outcomes, as well as of overall survival, in patients undergoing SRS.MethodsTo serve as neurological prognostic scores (NPSs), the authors scored 4 significant brain factors for both preservation of neurological function (qualitative survival) and prevention of neurological death (neurological survival) as 0 or 1 as described in the following: > 10 brain tumors = 0 or ≤ 10 = 1, total tumor volume > 15 cm3 = 0 or ≤ 15 cm3 = 1, MRI findings of localized meningeal dissemination (yes = 0 or no = 1), and neurological symptoms (yes = 0 or no = 1). According to the sum of NPSs, patients were classified into 2 subgroups: Subgroup A with a total NPS of 3 or 4 and Subgroup B with an NPS of 0, 1, or 2. The authors defined the modified BSBM according to the NPS subgroup classification applied to the original BSBM groups. The validity of this modified BSBM in 2838 consecutive patients with brain metastases treated with SRS was verified.ResultsPatients included 1868 with cancer of the lung (including 1604 with non–small cell lung cancer), 355 of the gastrointestinal tract, 305 of the breast, 176 of the urogenital tract, and 134 with other cancers. Subgroup A had 2089 patients and Subgroup B 749. Median overall survival times were 2.6 months in BSBM 0 (382 patients), 5.7 in BSBM 1 (1143), 11.4 in BSBM 2 (1011) and 21.7 in BSBM 3 (302), and pairwise differences between the BSBM groups were statistically significant (all p < 0.0001). One-year qualitative survival rates were 64.6% (modified BSBM 0A, 204 patients), 45.0% (0B, 178), 82.5% (1A, 825), 63.3% (1B, 318), 86.4% (2A, 792), 73.7% (2B, 219), 91.4% (3A, 268), and 73.5% (3B, 34). One-year neurological survival rates were 82.6% (0A), 52.4% (0B), 90.5% (1A), 78.1% (1B), 91.1% (2A), 83.2% (2B), 93.9% (3A), and 76.3% (3B), where A and B identify the subgroup. Statistically significant differences in both qualitative and neurological survivals between Subgroups A and B were detected in all BSBM groups.ConclusionsThe authors' new index, the modified BSBM, was found to be excellent for predicting neurological outcomes, independently of life expectancy, in SRS-treated patients with brain metastases.

Robustness of the neurological prognostic score in brain metastasis patients treated with Gamma Knife radiosurgery

“…We proposed using the NPS system for brain metastasis patients treated with GKRS as a means of predicting neurological outcomes such as qualitative and neurological survival. 9 NPS consists of 4 intracranial disease factors: brain tumor number, CITV, an MRI finding of localized leptomeningeal dissemination, and neurological symptoms. We classified NPS Group A as those patients for which better neurological outcomes could be expected and Group B as those patients with poorer anticipated outcomes.…”

“…In our previous study, we estimated qualitative and neurological survival by employing the Kaplan-Meier method. 9 However, these cumulative incidences tended to be overestimates compared with the true values because the Kaplan-Meier method does not take competing risk into consideration. 2 For example, neurological deterioration cannot be observed if patients experience systemic deterioration and vice versa.…”

“…We have highlighted the usefulness of incorporating NPS into established grading systems because this will provide very important information for selecting the optimal radiation treatment intensity when performing GKRS. 9 What is the best grading system into which NPS can be incorporated? For statistical reasons, RPA and SIR are not recommended.…”

“…Thus, neurological deterioration was defined as a KPS score that decreased to less than 70 due to intracranial disease progression. [9][10][11] The interval from the date of GKRS until the date of loss of functional independence was calculated. We categorized functional independence as "censored," neurological deterioration as "failure," and systemic deterioration as a "competing risk."…”

Neurosurgical management of brain metastases

“…74 Clinical decision making for these diverse patients also should incorporate the needs of the patient and requires a multidisciplinary team and integration of palliative care. 75 Over half of patients with brain metastases have capacity compromise in making medical treatment decisions.…”