Breast cancer characteristics in elderly women: A comprehensive cohort study of 7,965 patients

Purpose Breast cancer in older women is a major public health issue as there is an age-related excess mortality. Our aim was to study the tumor characteristics at diagnosis, treatment and outcomes in order to identify possible ways of improving breast cancer management in elderly women.

Methods We conducted a single-institution retrospective analysis on a cohort of 7,965 women with invasive breast cancer or Ductal Carcinoma in situ (DCIS) who were treated between 2001 and 2017. This cohort was constituted with a machine learning-based tool called SENOMETRY (NCT02810093) which allowed us to extract structured data from unstructured Electronic Health Records. Patients were divided in 3 groups according to the age at diagnosis: younger (< 49, N = 2001), middle-aged (50 to 74, N = 4859) and elderly (≥ 75, N = 1105).

Results In elderly women breast cancer had more favorable predictive factors (more estrogen receptors P < 0.001, less Human Epidermal growth-factor Receptor 2 overexpression P = 0.009) and prognostic factors (less Ki67 > 30 %, P = 0.001) factors. Tumors were diagnosed at a more advanced local stage (P < 0.001). Lymph node involvement decreased before 70 (ρ -0.033, P = 0.027) and increased again after this threshold (ρ +0.065, P = 0.021). Older women underwent heavier surgical procedures (P < 0.001 to 0.049) and more surgical abstention (P < 0.001) for invasive carcinomas while no difference was noted for patients with DCIS only (P ranged from 0.280 to 0.440). Older women had less chemotherapy (P < 0.001). Elderly women had higher overall mortality and lower locoregional recurrence (P < 0.001). Specific mortality increased with age after 75 (P = 0.042). No difference of relapse-free or overall survival was noted for axillary lymph node dissection compared to sentinel lymph node biopsy in elderly women, after adjustement on tumor size and lymph node involvement.

Conclusion Our findings suggest that axillary surgery de-escalation and earlier diagnosis would be and accessible way of improving breast cancer management in older women.