Metaplastic carcinoma of the breast: case series of a single centre

Fialho, M. Pinto; Gonçalves, L.; Ruivo, L.; Gradil, A.; Correia, L.

http://hdl.handle.net/10400.21/21671

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Abstract(s)

Background & objectives: Metaplastic carcinoma breast cancer (MpBC) is a rare and heterogeneous group of invasive breast carcinomas. Despite some studies and case reports data are currently limited. Our work aims to evaluate the clinicopathological features and the prognosis of MpBC patients. Methods: Retrospective unicentric study of MpBC diagnosed from January 2000 to February 2024. Pathological reports were accessed for specific patterns of MpBC, grouped as monophasic/biphasic tumors and TNM stratified according to WHO Breast Tumours 5th edition and AJCC 8th edition. Time-to-event outcomes were calculated using the Kaplan-Meier method and the log-rank test. Results: We identified 44 patients, 1 male, median age 59 years-old (33-98), 9 metastatic ad-initio. Biphasic-MpBC corresponded to 77%; heterologous-mesenchymal-differentiation was found in 34%, and spindle-cell carcinoma in 6.8%. Ki67 ranged from 20 to 95%. Twenty-seven were triple-negative, eight luminal-B, and six HER2-positive tumors. The median follow-up time was 82.1 months and the median overall survival (mOS) was 32.1 months. Subgroup analysis showed no statistically significant differences between monophasic/biphasic MpBC or histological patterns. Metastatic patients and patients over 60 years had a poorer prognosis (25.1 vs 115.5 months p=0.053; 20.0 months vs mOS have not reached p=0.001, respectively). In luminal-B patients, mOS were not reached (vs 32.1 months -triple-negative and 10.6 months -HER2). Conclusion: MpBC is rare, reported only in up to 2% of all invasive breast cancers. Given its uncommon nature, pathology reports lack uniformity. Establishing protocols is crucial to accurately identifying and reporting patterns to better determine treatment strategies. Our data suggests better outcomes regarding Luminal-B, non-metastatic patients. However, the limited number of patients prevented a statistically significant evaluation of differences between histological subtypes. Multicentric studies are needed to correlate demographic, histological, or immunohistochemistry factors with patients’ outcomes.

Keywords

Breast cancer Metaplastic carcinoma Clinicopathological features Prognosis

URI

http://hdl.handle.net/10400.21/21671

Citation

Fialho MP, Gonçalves L, Ruivo L, Gradil A, Correia L. Metaplastic carcinoma of the breast: case series of a single centre. In: 36th European Congress of Pathology, Convention Centre Dublin (Ireland), September 7-11, 2024. Virchows Arch. 2024;485(Suppl 1):S201.