Impact of Molecular Profiling of Breast Cancer on the Rate of Locoregional Recurrence in Young Versus Old Female Patients.

Background Breast cancer (BC) is diverse regarding its natural history and treatment responses. The traditional histopathological classification is unable to confine this diverse clinical heterogeneity. Classically, prognosis and treatment response are influenced by factors including histological grade, lymph node status, and tumour size. Recently, research has diverted from histological classification towards molecular classification. We aim to analyse the locoregional recurrence of breast cancer incidence following surgery across the different molecular subtypes as well as relation to age. Materials and methods Female patients diagnosed with a locoregional recurrence of breast carcinoma in 2012-2014 were identified from our centre histology department. We only included stage I-III patients who were previously treated with surgery achieving negative surgical margins and later developed locoregional recurrence during our study period. These patients were subdivided by age into old (≥40 years old) and young (<40 years old) groups according to their initial diagnosis age. Furthermore, they were categorised according to the molecular subtype of their primary tumour. Results Our study included 184 patients (124 designated to the old age group, 60 to the young age group). In the young group, recurrence occurred after a mean of 4.3 years and the range was one to 23 years, while in the old group, the mean was 3.8 years, and the range was one to 14 years. The most primary cancer subtype recorded was triple-negative (41.85%): 50 old patients and 27 young. Next was the Her-2/neu enriched subtype (27.72%): 35 old patients and 16 young, following this was luminal A subtype (21.19%): 27 old and 12 young. Last was the luminal B subtype (9.24%): 12 old patients and five young. Conclusions To conclude, in our series, the most common molecular subtype found in the recurrent cases was the luminal negative subtypes, with a relatively similar pattern across both age groups. The results of this study can be used as a basis for large prospective studies in our centre to further analyse the effect of molecular subtyping on the recurrence rates of BC.