Stereotactic radiation therapy of brain metastases: efficacy and toxicity of treatment

Introduction. Stereotactic radiation therapy (SRT) for metastatic brain damage is one of the main methods that contribute to achieving local control (LC) over the metastatic focus. However, despite an extensive number of scientific publications, the most effective and safe treatment regimen, as well as the factors influencing the development of radionecrosis (RN), are still not fully determined.

Aim. To evaluate the toxicity and effectiveness of the SRT course in patients with metastatic brain damage.

Materials and methods. This retrospective single-center study included all patients who underwent SRT for brain metastases from 2020 to 2024. Inclusion criteria: the ability to analyze data from 6-month and 1-year LC. The primary endpoint of the study is the effect of clinical, radiological, radiobiological, and dosimetric parameters on the incidence of RN. Secondary endpoints: RN frequency index, indicators of 6-month and 1-year LC.

Results. 62 patients with a total of 97 metastatic foci were included in the study. According to the results of the study, the development of RN was detected in 12.9 % (n = 8) of patients. When recalculating the RN frequency (n = 8), based on the total number of irradiated foci (n = 97), the RN frequency was 8.2 %. No factors influencing the development of RN have been identified. 6-month and 1-year control over irradiated foci was achieved in 54.8 % (n = 34) and 38.7 % (n = 24) of patients. Similar LC indices, based on the total number of irradiated foci, were 53.6 % (n = 52) and 34 % (n = 33), respectively. According to the results of a single- and multifactorial analysis, systemic therapy after a course of SRT affected the 6-month LC index for irradiated foci (odds ratio 7.53; 95 % confidence interval 2.49–22.7; p < 0.01). This factor also significantly affected the 6-month LC in patients (p = 0.01). The conformity index had a significant effect (p = 0.02) on the same indicator for irradiated foci according to the results of a single-factor analysis, but had no effect when conducting a multifactorial analysis. At the same time, no factors affecting the 1-year LC index were identified for both patients and irradiated foci.

Conclusions. The results obtained reflect the low toxicity of the SRT course with insufficient LC values. In turn, systemic drug therapy can play an important role in achieving control over the irradiated focus. Such data can become the basis for further optimization of the SRT course in patients with brain metastases, as well as for conducting new scientific research in this field of radiation therapy.

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