Introduction: To investigate the influence of ageing on the incidence of breast cancer (BC) molecular subtypes, patient age at diagnosis was correlated with bio-pathological data collected retrospectively from 2723 consecutive patients diagnosed/treated at our Institute between 2000 and 2003.
Methods: According to their bio-characteristics, 61% of the samples could be assigned to a molecular subtype: the "HER-2+", the "ER & HER2 negative" or one of the two "luminal-like" subtypes divided according to their histological grade ("A" [HER-2-/ER+/grade 1-2] and "B" [HER-2-/ER+/grade 3]).
Results and conclusion: Age is highly influencing the incidence of BC molecular subtypes. Patients younger than 40 develop a statistically higher rate of high grade proliferating "HER-2" (27%) and "ER & HER2 negative" (31%) BC whereas patients older than 50 develop mostly less aggressive hormone-dependant "luminal-A" BC (>67%). Nevertheless, a significant proportion of patients older than 70 develop "luminal-B" (19%) tumours associated with high proliferation, high grade, large size and nodal invasion.