Abstract PS14-27: Oncogenetic caracterization and imunohistochemistry patterns of male cancer breast diagnosticated in Haroldo JuaÇaba hospital, Northeast of Brazil

Abstract INTRODUCTION: The male breast cancer (MBC) is a rare disease, responsible for about 0.2% of all cancers and 0.1% of deaths for male cancer. Despite the rarity of the disease, statistics indicate that the incidence of MBC has been increasing significantly. The main risk factors for the development of MBC include old age, hormonal imbalance, radiation exposure, and family history of breast cancer. Hereditary breast and ovarian cancer (HBOC) is a syndrome associated with mutations in the BRCA1 and BRCA2 genes that have been related to MBC that as a rare disease, still poorly understood. METHODOLOGY: Family history analyzes, type and tumor staging, molecular markers expression, hormone receptors (RE, RP, and HER2), and cell proliferation marker (KI67) analysis were performed by immunohistochemistry. The presence of genetic mutations and the frequency of these mutations were evaluated in 31 genes of HBOC suspected patients treated at the Haroldo Juaçaba Hospital between the years 2009 to 2020. RESULTS: A total of 236 patients were diagnosed with breast cancer and submitted to a genetic test. Six of them were male patients aged between 54 and 73 years. His family history indicated that 83.3% had first-degree relatives affected by breast cancer. Different pathological staging was founded after tumors evaluation with the presence of micrometastases (P3) and higher levels of invasion in the lymph nodes. The expression of the cell proliferation marker (KI67) indicated low levels of expression except for patient P5. All patients presented expression of two hormone receptors (ER and RP) and no expression for HER2, except for one patient (P1), who had bilateral breast cancer, with HER2 expression (+2) on the right breast (first tumor) and no RP and HER2 expression in the left breast (second tumor), besides a moderate expression of KI67 (40%) (Table 1). The oncogenetic evaluation indicated that 83.33% of the patients had mutations described in the clinical database (ClinVar) 60% of them were pathogenic. The variants founded were in the PALB2 (16.66%), BRCA1 (33.33%), and BRCA2 (33.33%) genes (Table 1). The pathogenic mutations founded were located in the BRCA 1 and BRCA2 genes. One patient (P5) did not present mutations or VUS. The patient without the mutation (P5) presented a tumor with T3N1 pathological staging, low expression of estrogen (10%) and progesterone (10%) receptors, absence of HER2 expression, and high capacity of proliferation, indicated by the expression of KI67 (80%). The results indicate heterogeneity in the histological and molecular patterns of the patients evaluated, besides the oncogenetic patterns that may be associated with HBOC, especially those whose variants founded were pathogenic.CONCLUSION: Due to the low frequency of male breast cancer, the oncological data of these patients are relevant for epidemiological, pathological, and oncogenetic characterization, improving the characterization and identification of patterns for this pathology.Research Sponsor: Ministerio da Saude, Brasil (PRONON) Table 1. Histopathologic molecular markers and variation gene characterization of male breast cancer evaluated in Hospital Haroldo Juaçaba, Northest of Brazil, between 2009 and 2020. *VUS #Pathogenic variation.AgeFamiliar historyMolecular markersVariationPatientDiagnosticLast clinical evaluationBCOtherSubtype tumorPathological stagingRERPHER2KI67GeneSpecificityP14857YesPancreas; CCPLUMINAL A(R) pT1cpN1a(L) pT1B(R) 80%(L) 80%(R) 20%(L) negative(R) +2(L) negative(R) 18%(L) 40%PALB2*c. 3257G>A:Arg1086GlnP27274YesNoLUMINAL B(L)pT2 pN3a90%100%Negative20%BRCA1*c. 754C>T:Arg252CysP36466NoNoLUMINAL ApT2pN1mic90%70%Negative10%BRCA1#c. 5266dupC: p.Gln1756Pro fs74P45457YesNoLUMINAL A(L)T4bN290%90%Negative10%BRCA2#c. 4808delA: pAsn1603Thr fs14P55858YesProstaticLUMINAL A(R) T3N110%10%Negative80%Not detectedNot detectedP65858YesProstaticLUMINAL B(R) T4dN060%60%Negative30%BRCA2#c. 4808delA: pAsn1603Thr fs14 Citation Format: Maria Claudia dos Santos Luciano, Maria Júlia Barbosa Bezerra, Isabelle JoyceLima Silva-Fernandes, Paulo Goberlanio de Barros Silva, Clarissa Gondim Picanço-Albuquerque, Rosane Oliveira Sant´anna, Francisca Fernanda Barbosa Oliveira, Flavio Silveira Bitencourt, Marcos Venicio Alves Lima. Oncogenetic caracterization and imunohistochemistry patterns of male cancer breast diagnosticated in Haroldo JuaÇaba hospital, Northeast of Brazil [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS14-27.