Clinicopathological features, genetic alterations, and BRCA1 promoter methylation in Japanese male patients with breast cancer

Akihiko Shimomura, Masayuki Yoshida, Takashi Kubo, Satoshi Yamashita, Emi Noguchi, Aiko Nagayama, Toru Hanamura, Miki Okazaki, Toru Mukohara, Asako Tsuruga, Kiyo Tanaka, Yukino Kawamura, Toru Higuchi, Yoko Takahashi, Sasagu Kurozumi, Tetsu Hayashida, Hitoshi Ichikawa, Toshikazu Ushijima, Akihiko Suto

Research output: Contribution to journalArticlepeer-review


Purpose: Male breast cancer (MBC) is a rare cancer accounting for only 1% of all male cancers and is, therefore, poorly studied. We aimed to characterize the subtypes of MBC in Japanese patients based on genetic profiling, the presence of tumor-infiltrating cells, and the expression of immunohistochemical markers. Methods: This retrospective study included 103 patients with MBC diagnosed between January 2009 and December 2019 at various hospitals in Japan. Clinicopathological patient characteristics were obtained from medical records, and formalin-fixed paraffin-embedded tissue specimens were analyzed for histological markers, mutations of 126 genes, BRCA1 methylation, and stromal tumor-infiltrating lymphocytes. Results: The median patient age was 71 (range 31–92) years. T1-stage tumors were the most frequent (47.6%), and most were node negative (77.7%). The majority of tumors were positive for estrogen receptor (98.1%), progesterone receptor (95.1%), and androgen receptor (96.1%), and BRCA2 was the most frequently mutated gene (12.6%). The most common treatment was surgery (99.0%), either total mastectomy (91.1%) or partial mastectomy (7.0%). Survival analysis showed a 5-year recurrence-free survival rate of 64.4% (95% confidence interval [CI] 46.7–88.8) and a 5-year overall survival rate of 54.3% (95% CI 24.1–100.0). Conclusion: Japanese MBC is characterized by a high rate of hormonal receptor positivity and BRCA2 somatic mutation. Due to the observed clinicopathological differences in MBC between the Western countries and Japan, further prospective studies are needed to evaluate the most suitable treatment strategies.

Original languageEnglish
Pages (from-to)593-602
Number of pages10
JournalBreast Cancer Research and Treatment
Issue number3
Publication statusPublished - 2023 Feb


  • Biomarkers
  • Descriptive studies
  • Male breast cancer
  • Rare cancers
  • Translational research

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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