Metastasis patterns and prognosis of octogenarians with metastatic breast cancer: A large-cohort retrospective study

BACKGROUND: Breast cancer may differ biologically in patients aged over 80 years. The objective of the current study was to analyze the metastasis patterns and prognosis of elderly patients with metastatic breast cancer (MBC) and compare it to patients of other ages. METHODS: The Surveillance, Epidemiology, and End Results (SEER) database was utilized to select MBC patients from 2010 to 2015. Chi-squared test was used to compare clinicopathological characteristics among different aged groups. The Kaplan-Meier method and multivariate Cox model were utilized for survival analysis. RESULTS: A total of 10479 MBC patients were included, among which 1036 (9.9%) patients were aged over 80 years. Compared with other aged group, the elderly patients tended to have a higher proportion of HR+/Her2- subtype, white race, lower tumor differentiation, and receive less treatment, including surgery, chemotherapy and radiotherapy (P< 0.001). MBC patients with different age presented with distinctive metastatic patterns. The older patients were more likely to have lung metastasis, but less likely to have bone, brain, liver and multiple sites metastasis than the younger group (P <0.001). The proportion of TNBC subtype increased substantially in the older patients with brain metastasis, compared to the younger and middle-aged group. The old age was demonstrated to significantly associate with worse prognosis of MBC patients. Additionally, our findings also showed that older MBC patients could achieve dramatical overall survival benefit from surgery (HR = 0.58; P <0.001) and chemotherapy (HR = 0.59; P <0.001), but not the radiotherapy (HR = 0.96; P = 0.097). CONCLUSION: The elderly MBC patients presented with distinctive metastatic patterns, clinical characteristics, and prognostic outcomes compared with younger patients. Our findings could assist clinicians in making appropriate therapeutic decision.