A clinicopathological study of invasive apocrine carcinoma of the breast: a single centre experience

Abstract

Background & objectives: Breast cancer is a divergent and multiplex disease encompassing distinct histologic and molecular genetic types. The aim of the study was to analyse clinicopathologic characteristics of patients with apocrine breast carcinoma using integrated state of art technologies. Methods: We performed a study that included 17 cases that met the criteria for apocrine breast carcinoma diagnosed between 2015 and 2023 at the Institute of Pathology in Skopje. We used TruSight Tumour 15 Gene Panel (Illumina) to analyse gene mutations in nine patients. Furthermore, protein expression of α-methylacyl-CoA racemase (AMACR) was analysed. Results: The median age of the patients was 61,9 years. All the patients were diagnosed with histological grade three. The average tumour size was 3,46cm and positive lymph nodes were detected in 70,5% of the patients. Most of the patients presented at stage II and III (III 35, 3%; II: 47,0%; and I: 17,7%), and the mean Ki67 index was 30%. Majority of the cases (58,8%) were triple negative while HER-2 overexpression and/or amplification was detected in 41,2%. AMACR expression was detected in 73,3% of the cases. Clinically relevant genomic alterations were detected in of 66,7% of the patients. Most frequent altered genes were TP53 (66,7%), PIK3CA (11,1%) and ERBB2 (11,1%). Conclusion: Our study revealed that most of the cases were triplenegative with clinically relevant genomic alterations in more than 60% of the cases. These neoplastic lesions also have AMACR overexpression. The current evidence states that AR-positive breast carcinomas may have limited clinical benefit from adjuvant chemotherapy. Cancer genomic profiling of apocrine carcinomas emerges to be an optimistic approach that could reveal possible targets for individualized treatment.