Central nervous system metastases in breast cancer: the impact of age on patterns of development and outcome.

PURPOSE: The purpose of this study is to explore differences in the pattern and outcome of central nervous system (CNS) involvement in breast cancer by age at diagnosis. METHODS: A retrospective database of a tertiary cancer center yielded 174 consecutive patients with breast cancer who were diagnosed with CNS metastases in 2006-2019. Data on histopathology, characteristics of CNS involvement, treatments, and survival (at three time points during the disease course) were compared between patients aged ≤ 45 and > 45 years. Pearson Chi-square or Fisher exact test and Kaplan-Meier survival curves with log-rank test were used for statistical analyses. RESULTS: Study population was divided according to age at diagnosis of breast cancer. 65 patients were ≤ 45 years old and 109 patients > 45 years old. The younger group was characterized by longer median overall survival (117.1 months vs 88 months, p = 0.017) and longer interval between breast cancer diagnosis to development of CNS metastases (97.4 months vs 75.9 months, p = 0.026). Median survival after development of CNS disease was not significantly different (18.7 months vs 11.1 months, p = 0.341), although it was significantly longer in younger patients within the subgroup of patients with triple-negative disease (22.5 vs 7.9 months, p = 0.033). There were no between-group differences in number, location, and clinical presentation of CNS metastases or in systemic and CNS-directed treatment approaches. CONCLUSION: While the presentation of CNS involvement was similar between the different age groups, younger patients had significantly longer CNS-free interval and longer overall survival, and for the subgroups of triple-negative patients, younger age at breast cancer diagnosis was associated with longer survival after diagnosis of CNS disease.