3130 - The Effects of Income and Race in Patients Receiving SRS/FSRT for Brain Metastases: A Single Institution Retrospective Cohort

Purpose/Objective(s):

Lower socioeconomic status has been consistently associated with poorer prognosis across a range of cancer types. However, there exists conflicting evidence surrounding whether race and income impacts outcomes following stereotactic radiosurgery in patients with brain metastases. Here, we report the survival and clinical features of patients treated with stereotactic radiosurgery for brain metastases.

Materials/Methods:

Between 2015 and 2020, patients with brain metastases from a diverse range of primary histologies were treated with stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT). A public census database with median income by zip code was used to categorize patients into four quartiles of income with the 4^th quartile as the highest. Association between race, income, and survival were assessed using Kaplan-Meier survival curves and cox proportional hazard models. The survival time was measured in months from 1^st SRS start until death or last follow-up. A log-rank test was used to compare survival distributions across racial and income groups. The association between race, income quartile, and other clinical variables (e.g., primary cancer type, prior systemic therapy, prior immunotherapy) was assessed using Chi-squared, Mann-Whitney U, and Kruskal-Wallis testing where appropriate.

Results:

320 patients (median age 62) received SRS/FSRT to 596 brain metastases. The two most common dose and fractionation schedules were 20Gy in a single fraction (131 patients [42%]) and 27Gy in 3 fractions (84 patients [27%]). The two most common histologies were non-small cell lung cancer, NSCLC, (136 patients [43%]) and breast cancer (45 patients [14%]). The median follow-up was 19.5 months. The median overall survival was 18.5 months. On survival analysis, there was no association between survival and income or race. On chi-squared analysis income quartile was associated with race, ECOG status at consult, receipt of prior chemotherapy and immunotherapy (all p < 0.001). The lowest quartile of income had more ECOG 2+ patients while the highest quartile had more patients receive systemic therapy prior to SRS. Income quartile was not associated with primary tumor histology. Black race was associated with having an ECOG of 2+. White race was associated with receipt of systemic therapy prior to SRS. Among White patients, receipt of chemotherapy prior to SRS was more common among individuals in higher income quartiles (p<0.005).

Conclusion:

In patients receiving SRS/FSRT for their brain metastases, neither income quartile nor race was associated with survival outcomes after treatment. However, both income quartile and race were associated with receipt of systemic therapies prior to SRS which raises questions about access to care. These findings add to a growing understanding of the effects of socioeconomic factors on the outcomes and treatment of patients undergoing SRS.