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Gene expression profiling of primary male breast cancers reveals two unique subgroups and identifies N-acetyltransferase-1 (NAT1) as a novel prognostic biomarker
Department of Oncology, Clinical Sciences and CREATE Health Strategic Center for Translational Cancer Research, Lund University, Lund.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Oncology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Centre for Clinical Research, County of Västmanland.
Department of Oncology, Clinical Sciences, Lund University, Lund, Sweden.
Department of Oncology, Clinical Sciences and CREATE Health Strategic Center for Translational Cancer Research, Lund University, Lund.
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2012 (English)In: Breast Cancer Research, ISSN 1465-542X, Vol. 14, no 1, R31- p.Article in journal (Refereed) Published
Abstract [en]


Male breast cancer (MBC) is a rare and inadequately characterized disease. The aim of the present study was to characterize MBC tumors transcriptionally, to classify them into comprehensive subgroups, and to compare them with female breast cancer (FBC).


A total of 66 clinicopathologically well-annotated fresh frozen MBC tumors were analyzed using Illumina Human HT-12 bead arrays, and a tissue microarray with 220 MBC tumors was constructed for validation using immunohistochemistry. Two external gene expression datasets were used for comparison purposes: 37 MBCs and 359 FBCs.


Using an unsupervised approach, we classified the MBC tumors into two subgroups, luminal M1 and luminal M2, respectively, with differences in tumor biological features and outcome, and which differed from the intrinsic subgroups described in FBC. The two subgroups were recapitulated in the external MBC dataset. Luminal M2 tumors were characterized by high expression of immune response genes and genes associated with estrogen receptor (ER) signaling. Luminal M1 tumors, on the other hand, despite being ER positive by immunohistochemistry showed a lower correlation to genes associated with ER signaling and displayed a more aggressive phenotype and worse prognosis. Validation of two of the most differentially expressed genes, class 1 human leukocyte antigen (HLA) and the metabolizing gene N-acetyltransferase-1 (NAT1), respectively, revealed significantly better survival associated with high expression of both markers (HLA, hazard ratio (HR) 3.6, P = 0.002; NAT1, HR 2.5, P = 0.033). Importantly, NAT1 remained significant in a multivariate analysis (HR 2.8, P = 0.040) and may thus be a novel prognostic marker in MBC.


We have detected two unique and stable subgroups of MBC with differences in tumor biological features and outcome. They differ from the widely acknowledged intrinsic subgroups of FBC. As such, they may constitute two novel subgroups of breast cancer, occurring exclusively in men, and which may consequently require novel treatment approaches. Finally, we identified NAT1 as a possible prognostic biomarker for MBC, as suggested by NAT1 positivity corresponding to better outcome.

Place, publisher, year, edition, pages
2012. Vol. 14, no 1, R31- p.
National Category
Cancer and Oncology
URN: urn:nbn:se:uu:diva-172739DOI: 10.1186/bcr3116ISI: 000307444100040PubMedID: 22333393OAI: diva2:515477
Available from: 2012-04-13 Created: 2012-04-13 Last updated: 2012-10-02Bibliographically approved
In thesis
1. Characterization of Male Breast Cancer: From Molecule to Clinical Outcome
Open this publication in new window or tab >>Characterization of Male Breast Cancer: From Molecule to Clinical Outcome
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of this thesis was to investigate different aspects of male breast cancer (MBC), and to compare these with findings in female breast cancer (FBC). In paper I, a population–based study was performed to investigate possible differences in treatment and outcome between MBC and FBC patients. MBC and FBC presented with a similar distribution of stage. Although no differences in primary treatment strategy were demonstrated, MBC patients had significantly poorer overall and relative survival, indicating a more aggressive disease. Paper II aimed to assess the value of clinicopathological factors and molecular subtypes in MBC. One hundred and ninety-seven MBC tumors were characterized using immunohistochemistry (IHC) and the findings were correlated to outcome. Lymph node positivity, larger tumor size and ER-negativity were independent risk factors for breast cancer death. Tumor grade, HER2, Ki 67 or IHC classification into molecular subtypes did not demonstrate any prognostic information. In paper III, the same patient material as in paper II was used for evaluation of proliferation markers. High levels of cyclin A and cyclin B expression and an elevated mitotic count were predictive of breast cancer death. Ki-67 was re-evaluated using different cut-offs, but no prognostic value could be demonstrated. Contrarily, overexpression of cyclin D1 was associated with a lower risk of breast cancer death. In papers IV-V, the molecular background of MBC tumors was investigated.  Global GEX analyses were performed and two novel subgroups of MBC tumors were identified; luminal M1 and luminal M2. When comparing the degree of similarity with the “intrinsic” subtypes in FBC tumors, more than half of the MBC tumors remained unclassified.  Comparative genomic hybridization was used to investigate DNA aberrations. Two MBC subgroups were identified, of which one did not resemble any of the female subgroups. In both studies on the molecular level, a majority of patients were classified into the subgroup with a more aggressive tumor behavior. In conclusion, MBC seems to be a unique tumor entity. The established molecular subtypes in FBC are not applicable in MBC. Other prognostic profiles, specific for MBC, need to be identified.


Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 65 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 771
male breast cancer, immunohistochemistry, prognostic, cyclins, gene expression, genomic profiling
National Category
Cancer and Oncology
Research subject
Oncology; Oncology
urn:nbn:se:uu:diva-172670 (URN)978-91-554-8356-2 (ISBN)
Public defence
2012-06-02, Aulan, Ingång 21, Västmanlands sjukhus Västerås, Västerås, 13:15 (Swedish)
Available from: 2012-05-11 Created: 2012-04-12 Last updated: 2012-08-01Bibliographically approved

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