Re-irradiation in patients with progressive or recurrent brain metastases from extracranial solid tumors: A novel prognostic index

Abstract

Background: Most studies evaluating factors associated with the survival of patients with brain metastases (BM) have focused on patients with newly diagnosed BM. This study aimed to identify prognostic factors associated with survival after brain re-irradiation in order to develop a new prognostic index.

Methods: This 5-year retrospective study included patients treated with repeat-radiotherapy for recurrent BM at the "Instituto Nacional de Cancerología" of Mexico between 2015 and 2019. Significant variables in the multivariate Cox regression analysis were used to create the brain re-irradiation index (BRI). Survival and group comparisons were performed using the Kaplan-Meier method and the log-rank test.

Results: Fifty-seven patients receiving brain re-irradiation were identified. Most patients were women (75.4%) with a mean age at BM diagnosis of 51.4 years. Lung and breast cancer were the most prevalent neoplasms (43.9% each). Independent prognostic factors for shorter survival after re-irradiation were: Age >50 years (hazard ratio [HR]:2.5 [95% confidence interval [CI], 1.1-5.8]; p = 0.026), uncontrolled primary tumor (HR:5.5 [95% CI, 2.2-13.5]; p < 0.001), lesion size >20 mm (4.6 [95% CI, 1.7-12.2]; p = 0.002), and an interval <12 months between radiation treatments (HR:4.3 [95% CI, 1.7-10.6]; p = 0.001). Median survival (MS) after re-irradiation was 14.6 months (95% CI, 8.2-20.9).MS of patients stratified according to the BRI score was 17.38, 10.34, and 2.82 months, with significant differences between all groups.

Conclusions: The new BRI can be easily implemented for the prognostic classification of cancer patients with progressive or recurrent BM from extracranial solid tumors.

Keywords: prognostic index score; recurrent brain metastases; re-irradiation; repeat radiotherapy.

FIGURE 1

Brain metastases progression and recurrence rates. (A) Rate of brain metastasis recurrence in 57 after a first course of brain radiation and after re‐irradiation (B). Dashed lines indicate the proportion of patients with recurrence to the central nervous system at 12 and 24 months

FIGURE 2

Survival after repeat radiation. Kaplan–Meier curve showing the median survival after repeat radiation (in months) of 57 patients classified according to (A) the new BRI score; (B) primary tumor site; (C) the RPA score; (D) Pooled DS‐GPA (n = 52); (E) The Lung‐molecular GPA score for Non–Small‐Cell Lung Cancer (n = 25); (F) the breast cancer GPA (n = 25)