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

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. 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. 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. 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.