Effect of Breast Cancer Receptor Subtypes and CSF Cytology Status on Survival of Patients With Leptomeningeal Disease.

BACKGROUND

It is unclear whether breast cancer (BC) subtypes or CSF cytology results are associated with overall survival (OS) among patients with BC leptomeningeal disease (LMD). This single-institution retrospective study compares OS among BC patients with LMD across various breast cancer subtypes and CSF cytology results.

METHODOLOGY

The study enrolled BC patients diagnosed with LMD between 2010 and 2023. Breast cancer subtypes were classified as A. ER+/HER2-, HER2+, or triple-negative BC (TNBC); B. HER2+, HER2-Low, HER2-Zero. CSF cytology subtypes included CSF+, CSF-, or CSF not tested (NT). OS was summarized via Kaplan-Meier analysis and compared using log-rank test. Cox models were used for multivariate analyses.

RESULTS

Out of 69 patients registered, median OS (95% CI) for ER+/HER2- (n = 33), HER2+ (n = 12) and TNBC (n = 24) subtypes were 8.0 (3.02, 24.8), 5.71 (1.61, not estimated) and 3.2 (1.11, 4.95) months (P = .17). In multivariate analysis, TNBC was associated with worse OS versus ER+/HER2- [Hazard Ratio (HR), 95% CI: 2.64, 1.23-5.80, P = .04]. HER2 subtypes (HER2-Zero, n = 21; HER2-Low, n = 32; HER2+, n = 12) showed no significant differences in OS. Median OS (95% CI) for CSF+ (n = 16), CSF- (n = 18), and CSF NT (n = 35) groups were 3.54 (1.61, 12.72), 13.41 (4.95, 61.93) and 3.28 (1.44, 6.92) months (P = .04). Multivariate analysis showed both CSF+ and CSF NT were associated with shorter OS compared to CSF- group [HR (95% CI) 4.50 (1.75, 12.11) for CSF+ vs. CSF-; 2.91 (1.45, 6.26) for CSF NT vs. CSF-; P = .002].

CONCLUSION

TNBC LMD group was associated with worse OS than ER+/HER2- BC LMD when adjusting for other prognostic factors. CSF- LMD patients had better OS than CSF+ or CSF NT LMD.