Impact of Age in Women with Stage I-III Triple Negative Breast Cancer (TNBC): A National Cancer Data Base (2004-2014) Report

Abstract

Young age has been associated with worse overall survival (OS) in breast cancer patients. While the cause of this is likely multi-factorial, this has been in part attributed to the higher prevalence of the aggressive triple-negative disease in younger cohorts. However, it remains unclear if younger age predicts for worse survival in patients with TNBC. In this study we aimed to assess the impact of age on survival in women with stage I-III TNBC. Women with stage I-III TNBC diagnosed between 2004-2014 were identified in the National Cancer Data Base. Patients with male sex, in situ disease, metastatic disease, or incomplete information were excluded from the analysis. We analyzed demographic factors as well as disease- and treatment-related factors by age group. Statistical analyses including Kaplan-Meier estimates and Cox proportional hazards were calculated for treatment- and disease-related factors. Patients were divided into 4 age-based groups for this analysis, age <36, 36-50, 51-65, and >65. A total of 48,248 women (range 18-90, median 57) were identified in the database with median follow-up of 38 months (range 0.1 to 86.67 months). On univariate analysis, women age <36 did not have a statistically significant difference in OS when compared to women age 36-50 (HR = 0.949, 95% CI 0.841-0.1071, p = 0.3979) or women age 51-65 (HR = 1.078, 95% CI 0.958-1.212, p = 0.2142). Women age >65 had a statistically significant decrease in OS in comparison with women age <36 (HR = 2.030, 95% CI 1.804-2.284, p = <0.0001) in univariate analysis. Increasing T and N stages were associated with decreased OS in all patients except in the T2 stage group (HR = 0.984, 95% CI 0.889-1.091, p = 0.7640) when compared with the T1 and N1 stage groups. However, the different cohorts had similar distribution of stage I, II and III patients. Multivariable Cox proportional hazards model did not demonstrate an increased mortality in the younger patients in comparison with the older patients. When compared to older cohorts, virtually all younger patients underwent chemotherapy and had higher levels of neoadjuvant and combined neoadjuvant and adjuvant chemotherapy, higher rates of mastectomy, and higher rates of post-mastectomy radiation (chi-squared p-value = <0.0001 for all comparisons). These data demonstrate that stage-matched younger patients with TNBC do not have a decreased OS when compared to their older counterparts. However, younger patients tended to have more aggressive chemotherapy and surgery which likely underlies the lack of difference in survival in the younger age groups compared to the older age groups. Thus, younger women do not have worse survival, but may continue to require more aggressive treatment to achieve similar survival rates to their older counterparts.