Influence of advanced age on the prognosis of triple-negative breast cancer patients: A surveillance, epidemiology, and end results-based study.

Abstract

Introduction: Age at diagnosis has shown significant effect on the prognosis in breast cancer patients. However, whether age is an independent risk factor remains controversial. Furthermore, population-based estimates of age on the prognosis impact in triple-negative breast cancer are still lacking. The aim of this study was to analyze the influence of age and other factors on the prognosis and survival of triple-negative breast cancer patients.

Materials and methods: We used the surveillance, epidemiology, and end results program data from 2011 to 2014. A retrospective cohort study was conducted to investigate prognosis factors in triple-negative breast cancer. Patients were divided into two groups according to age at diagnosis: 75 + years (the elderly patients) and < 75 years (reference group). The clinicopathologic characteristics of different age groups were compared using Chi-square tests. Overall survival (OS) and breast cancer-specific survival were analyzed using the Kaplan-Meier method. Prognostic factors were compared using the Cox proportional hazards model. We also analyzed the difference of distant metastasis at initial diagnosis on every group.

Results: A total of 21,429 triple-negative breast cancer patients were included in our study. The mean breast cancer-specific survival time of triple-negative breast cancer was 70.5 months for the reference group and 62.4 months for the elderly group. Survival analysis showed that the breast cancer-specific survival rate was 78.9% for the reference group and 67.4% for the elderly group. The mean OS time was 69.0 months for the reference group and 52.3 months for the elderly group. The 5-year OS of triple-negative breast cancer patients was 76.4% for the reference group and 51.3% for the elderly group. The prognosis of elderly patients is much poor than reference group. Univariate Cox regression analysis showed that age, race, marital status, histological grade, stage, T, N, M, surgery, radiotherapy, and chemotherapy were risk factors for triple-negative breast cancer (TNBC) (P < 0.05). Multivariate Cox regression analysis showed that age, race, marital status, histological grade, stage, T, N, M, surgery, radiotherapy, and chemotherapy were independent risk factors for TNBC (P < 0.05).

Conclusions: Age is an independent risk factor for the prognosis of TNBC patients. Elderly triple-negative breast cancer patients displayed obvious lower 5-year survival rate compared to reference group, even though they have better grade stage, minor tumor, less lymph node metastasis. The lower rate of marital status, radiotherapy, chemotherapy, surgery, and higher rate of metastasis at diagnosis must contribute to their poor outcome.