Correlation between Molecular Subtypes and the Prognosis in Elderly Women with Breast Cancer: A Case-control Study

  Objective  The aim of this retrospective study was to analyze the distribution of molecular subtypes and its impact on the prognosis of elderly women with breast cancer(BC).

  Methods  Elderly women with BC who received an operation between January 1st, 2010 and June 30th, 2016 were reviewed. Information on epidemiological characteristics, operation, pathology, adjuvant therapy, and outcome were collected based on the hospital-based database and routine follow-up. Kaplan-Meier analysis and Cox proportional hazards model were applied to pursue the correlation between molecular subtypes and disease-free survival (DFS)/overallsurvival(OS).

  Results  A total of 502 elderly women with BC who met the inclusive and exclusive criteria were enrolled, with an average age of (76.65±4.36)years old, including 401(79.88%) cases of luminal BC, 39(7.77%) of Her-2 rich BC, and 62(12.35%) of triple-negative BC(TNBC). At a median follow-up of 60 months, 8.37%(42/502) of the patients suffered from local recurrence and/or metastasis, and 11 of 50 deaths were of breast cancer. Survival analysis indicated that the molecular subtype had a significant correlation with DFS(P < 0.001) and OS(P=0.040). Compared with the luminal A subgroup, there were more local recurrence or metastasis in the luminal B2(HR=4.306, 95% CI:1.469-12.618, P=0.008), Her-2 rich(HR=3.729, 95% CI:1.418-9.809, P=0.008), and TNBC(HR=2.580, 95% CI:1.045-6.367, P=0.040) subgroups. Compared with the luminal A subgroup, there were more deaths in the Her-2 rich subgroup (HR=3.219, 95% CI:2.762-3.676, P=0.010).

  Conclusions  The molecular subtype has a significant correlation with DFS and OS in elderly women with BC. Luminal B2, Her-2 rich, and TNBC subgroups indicate high risk of local recurrence and distant metastasis.