# Male breast cancer

Source: https://onco.cc/cancers/male-breast-cancer/  
OnCo record `male-breast-cancer` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Men get breast cancer too, usually a hormone-sensitive kind found as a lump near the nipple. It is treated much as in women, with surgery, radiotherapy and tamoxifen, and inherited BRCA2 mutations are found often enough that every man diagnosed is offered genetic testing. The main fix under way is including men in trials so their care stops being borrowed from women.

## Summary

Male breast cancer is almost always invasive ductal carcinoma, oestrogen-receptor positive (in the large majority) and HER2-negative; lobular carcinoma is rare because men lack terminal lobules, and triple-negative disease is uncommon. Germline BRCA2 mutations are the strongest hereditary factor (BRCA1 less so), and testing is recommended for every man with breast cancer regardless of age or family history; other risks are Klinefelter syndrome, oestrogen exposure, radiation, obesity and liver disease. Men present later and with higher stage than women because there is no screening and awareness is low, and the tumour sits close to the skin and nipple.

Treatment follows the female algorithm with adjustments. Mastectomy is usual because of tumour position, though breast-conserving surgery is feasible in some; sentinel node biopsy, radiotherapy and chemotherapy indications mirror women's. Endocrine therapy differs: tamoxifen is the preferred adjuvant agent, because aromatase inhibitors used alone in men raise testosterone and oestradiol through feedback and appear less effective, so if used they should be combined with a GnRH agonist. CDK4/6 inhibitors, HER2-directed therapy and PARP inhibitors for germline BRCA carriers are used in men on the basis of extrapolation and small cohorts. The EORTC 10085 / International Male Breast Cancer Program (Ann Oncol 2018) was the largest characterisation effort, and the FDA's 2020 guidance 'Male Breast Cancer: Developing Drugs for Treatment' instructs sponsors to include men in breast cancer trials rather than excluding them by default.

Open problems are adjuvant endocrine adherence and side effects in men, the biology of male-specific ER-positive disease, and the paucity of prospective data.

## Fields

- Kind: Cancer
- Last checked: 2026-09-10
- Also known as: Breast cancer in men
- Tags: nci-coverage; rare; breast
- Group: breast
- Burden: About one in a hundred breast cancers occurs in a man; the lifetime risk is roughly one in a thousand men, higher with a BRCA2 mutation, Klinefelter syndrome or a strong family history (SEER; NCI).
- Subtypes: Invasive ductal carcinoma, ER-positive / HER2-negative (most); HER2-positive (minority); Triple-negative (rare); Ductal carcinoma in situ (often papillary); Hereditary (BRCA2, BRCA1, PALB2, CHEK2)
- Biomarkers: ER, PR, HER2 (as in women); Germline BRCA1/2 and multigene panel (recommended for all men with breast cancer); Ki-67 and genomic assays (Oncotype DX validated mainly in women); Nodal status; Testosterone and oestradiol if aromatase inhibitors are considered

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/male-breast-cancer/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/male-breast-cancer/#overview [4 state-of-the-art points]
- What it is (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/male-breast-cancer/#what-it-is [5 subtypes]
- Finding it (on the hub): How it shows itself, how it is confirmed, what screening exists, and the biomarkers clinicians test for. https://onco.cc/cancers/male-breast-cancer/#finding-it [5 biomarkers]
- Treating it (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/male-breast-cancer/#treating-it [4 settings, 4 decisions with options]
- Evidence (on the hub): Trials recruiting now, the landmark trials, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/male-breast-cancer/#evidence [2 trials, 2 key papers, 6 milestones]
- The science (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/male-breast-cancer/#science [5 targets, 2 pathways]
- Where you are (own page): Cases by country, the UK and NHS pathway and other country lenses, and the expert centres with trials on record. https://onco.cc/cancers/male-breast-cancer/where-you-are/
- Living with it (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/male-breast-cancer/#living-with-it [18 questions, 6 red cards]
- What is coming (own page): Everything in development, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/male-breast-cancer/coming/ [11 medicines, 1 trial, 4 open problems]
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/male-breast-cancer/data/ [54 connected records]

## Standard of care

- Early stage: Mastectomy (or breast conservation where feasible) with sentinel node biopsy; adjuvant radiotherapy by the same criteria as women; chemotherapy and HER2-directed therapy as indicated. ([Mastectomy](https://onco.cc/terms/mastectomy/), [Sentinel lymph node biopsy](https://onco.cc/technologies/sentinel-node/), [Trastuzumab](https://onco.cc/drugs/trastuzumab/))
- Adjuvant endocrine, ER-positive: Tamoxifen for five to ten years; aromatase inhibitor only with GnRH agonist suppression if tamoxifen is contraindicated. ([Tamoxifen](https://onco.cc/drugs/tamoxifen/), [Goserelin / leuprolide (ovarian function suppression)](https://onco.cc/drugs/goserelin/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/))
- Advanced, ER-positive: Endocrine therapy (tamoxifen, or aromatase inhibitor or fulvestrant with GnRH agonist) with a CDK4/6 inhibitor by extrapolation; chemotherapy for visceral crisis. ([Tamoxifen](https://onco.cc/drugs/tamoxifen/), [Fulvestrant](https://onco.cc/drugs/fulvestrant/), [Palbociclib](https://onco.cc/drugs/palbociclib/), [Ribociclib](https://onco.cc/drugs/ribociclib/), [Abemaciclib](https://onco.cc/drugs/abemaciclib/))
- Germline BRCA carriers: PARP inhibitor (olaparib adjuvant per OlympiA; olaparib or talazoparib for metastatic disease) and cascade testing of relatives. ([Olaparib](https://onco.cc/drugs/olaparib/), [Talazoparib](https://onco.cc/drugs/talazoparib/), [Germline (hereditary) testing](https://onco.cc/technologies/germline-testing/), [OlympiA](https://onco.cc/trials/olympia/))

## State of the art

- Guidelines (ASCO 2020, NCCN) now state explicitly how to treat men rather than leaving it to inference from women's trials.
- Universal germline testing in men with breast cancer finds BRCA2 mutations often and opens PARP inhibitor therapy and family cascade testing.
- The FDA's 2020 guidance pushes sponsors to include men in breast cancer trials; labels for CDK4/6 inhibitors and other agents increasingly cover men.
- The International Male Breast Cancer Program built the first large prospective registry, showing high ER positivity, low HER2 rates and under-treatment with adjuvant endocrine therapy.

## Open problems

- Men are still under-enrolled in breast cancer trials; regulatory guidance and label harmonisation are the response.
- Aromatase inhibitor efficacy and the need for GnRH co-treatment rest on small studies; registries are collecting outcomes.
- Later diagnosis from low awareness; education campaigns and rapid referral pathways are the levers.
- Adjuvant endocrine adherence and side effects in men are poorly studied.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Male_breast_cancer
- NCI PDQ: male breast cancer: https://www.cancer.gov/types/breast/male-breast-cancer
- ASCO guideline: management of male breast cancer (JCO 2020): https://doi.org/10.1200/JCO.19.03120
- FDA guidance: Male Breast Cancer, Developing Drugs for Treatment (2020): https://www.fda.gov/regulatory-information/search-fda-guidance-documents/male-breast-cancer-developing-drugs-treatment
- International Male Breast Cancer Program (Ann Oncol 2018): https://doi.org/10.1093/annonc/mdx651

## Connected records

- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [Ductal carcinoma in situ (DCIS)](https://onco.cc/cancers/ductal-carcinoma-in-situ/), [HER2-positive breast cancer](https://onco.cc/cancers/breast-her2-positive/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Phyllodes tumour of the breast](https://onco.cc/cancers/phyllodes-tumour/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [CDK4/6 inhibitors](https://onco.cc/technologies/cdk46-inhibitor/), [Endocrine therapy (SERMs, AIs, SERDs)](https://onco.cc/technologies/endocrine-therapy/), [Germline (hereditary) testing](https://onco.cc/technologies/germline-testing/), [Mammography & tomosynthesis](https://onco.cc/technologies/mammography/), [PARP inhibitors](https://onco.cc/technologies/parp-inhibitor/), [Sentinel lymph node biopsy](https://onco.cc/technologies/sentinel-node/)
- targets: [BRCA1 / BRCA2 (HRD)](https://onco.cc/targets/brca/), [CDK4/6](https://onco.cc/targets/cdk4-6/), [Estrogen receptor (ERα)](https://onco.cc/targets/estrogen-receptor/), [HER2](https://onco.cc/targets/her2/), [PARP](https://onco.cc/targets/parp/)
- drugs: [Abemaciclib](https://onco.cc/drugs/abemaciclib/), [Fulvestrant](https://onco.cc/drugs/fulvestrant/), [Goserelin / leuprolide (ovarian function suppression)](https://onco.cc/drugs/goserelin/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/), [Olaparib](https://onco.cc/drugs/olaparib/), [Palbociclib](https://onco.cc/drugs/palbociclib/), [Ribociclib](https://onco.cc/drugs/ribociclib/), [Talazoparib](https://onco.cc/drugs/talazoparib/), [Tamoxifen](https://onco.cc/drugs/tamoxifen/), [Trastuzumab](https://onco.cc/drugs/trastuzumab/), [Trastuzumab deruxtecan](https://onco.cc/drugs/trastuzumab-deruxtecan/)
- pathways: [Double-strand break repair: HR versus end joining](https://onco.cc/pathways/homologous-recombination-repair/), [Oestrogen receptor signalling](https://onco.cc/pathways/er-signaling/)
- terms: [Germline BRCA mutation (gBRCA)](https://onco.cc/terms/gbrca-mutation/), [Hereditary cancer syndromes](https://onco.cc/terms/hereditary-cancer-syndromes/), [Hormone receptor status (ER / PR)](https://onco.cc/terms/hormone-receptor-status/), [Mastectomy](https://onco.cc/terms/mastectomy/)
- trials: [OlympiA](https://onco.cc/trials/olympia/), [Phase III Study ：SHR6390/Placebo Combined With Endocrine Therapy for the Adjuvant Treatment of Hormone Receptor Positive,Human Epidermal Receptor 2 Ne](https://onco.cc/trials/nct04842617/)
- bottlenecks: [Inherited risk is mostly unidentified](https://onco.cc/bottlenecks/b-hereditary-risk/), [Rare and paediatric cancers without markets](https://onco.cc/bottlenecks/b-rare-cancers/), [Trials do not represent the people who get cancer](https://onco.cc/bottlenecks/b-trial-diversity/)
- key papers: [Characterization of male breast cancer: results of the EORTC 10085/TBCRC/BIG/NABCG International Male Breast Cancer Program](https://onco.cc/key-papers/paper-cardoso-ann-oncol/), [Management of Male Breast Cancer: ASCO Guideline](https://onco.cc/key-papers/paper-hassett-j-clin-oncol/)
- journals: [Breast cancer](https://onco.cc/journals/breast-cancer-jbcs/), [Breast cancer research](https://onco.cc/journals/breast-cancer-research/), [Breast cancer research and treatment](https://onco.cc/journals/breast-cancer-research-and-treatment/), [Clinical breast cancer](https://onco.cc/journals/clinical-breast-cancer/), [The Breast](https://onco.cc/journals/the-breast/), [The breast journal](https://onco.cc/journals/the-breast-journal/)

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JSON: https://onco.cc/api/v1/entities/male-breast-cancer.json