Breast Cancer at Extreme Ages - a Comparative Analysis in Chile

Background: Young onset breast cancer (BC) has a worse outcome as compared to in the elderly. However, some studies have shown that BC in the elderly, despite indolent features, does also cause increase in mortality. In an attempt to compare clinic-pathological characteristics, BC subtypes and survival in patients with BC presenting at extremes of age, we performed a retrospective study. Materials and Methods: Patients were either ${\leq}40$ or ${\geq}70$ years old. Subtypes were defined using immunohistochemistry and histological grade. Chi-Square test was used for evaluation of categorical variables, and Kaplan-meier and log-rank for disease-specific survival (DSS) and disease free survival (DFS). Results: We analyzed 256 patients ${\leq}40$ and 366 patients ${\geq}70$. Younger patients presented with more aggressive disease, with less luminal A but more luminal B and triple negative (TN) subtype. With a median follow-up of 57.5 months, DFS at 5 years in younger patients was 72.3% vs 84.6% in the elderly (p=0.007). Luminal A and B disease presented with worse DFS in younger patients. The opposite was seen in the TN subgroup. Although we found no significant differences in DSS, older patients with TN tumors died of BC more frequently. This group also received less chemotherapy. Conclusions: Young patients present with more aggressive disease, this translating into worse DFS. However, elderly patients with TN disease represent a particular subpopulation with worse DFS and DSS, suggesting that chemotherapy should not be withheld only because of age.