Breast cancer

Breast Cancer (Mammary Carcinoma): Facts, Early Detection and Treatment

The Disease at a Glance

Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer-related death among women worldwide.¹ In Switzerland, 6’860 women and 60 men are diagnosed with breast cancer each year — accounting for 32% of all cancers in women.² Each year, 1’405 women and 5 men die from the disease in Switzerland; the 5-year survival rate is 89%.²

 

Breast cancer represents a group of molecularly distinct cancers and is classified according to hormone receptor and HER2 status.³ Hormone receptor-positive breast cancer (HR+) is the most common subtype, accounting for approximately 70%; it is driven by oestrogen and/or progesterone and treated with endocrine therapy.10 A positive HER2 status is observed in 15–30% of breast cancer cases.6 While HER2-positive breast cancer was long considered particularly aggressive, the development of targeted therapies — including monoclonal antibodies, tyrosine kinase inhibitors and antibody-drug conjugates — has significantly improved prognosis.7,10 The greatest therapeutic challenge today is triple-negative breast cancer (TNBC), which lacks these targets and for which systemic treatment is primarily based on chemotherapy.10

Key Figures

Mortality

665’684
Women died from breast cancer worldwide in 2022¹

Distribution

32%
of all cancer cases in women in Switzerland are breast cancer²

Poor-prognosis.png

Poor prognosis

89%
5-year survival rate — early detection is crucial2,13

Risk Factors

The most important risk factors for developing breast cancer are female sex and age: breast cancer occurs approximately 100 times more frequently in women than in men,³ and 80% of all breast cancers in Switzerland are diagnosed from the age of 50 onwards.⁴


Additional risk factors can be divided into three categories:3,5


Non-modifiable factors

  • Family history/heredity — including BRCA1/2 mutations
  • High mammographic density
  • Situational hormonal imbalance
  • History of chest radiation (as part of radiotherapy)

 

Modifiable lifestyle factors

  • Smoking
  • Alcohol consumption
  • Unhealthy diet (e.g. high-fat diet)
  • Overweight and type 2 diabetes
  • Low physical activity

 

Medical factors

  • Hormone replacement therapy during menopause

Genetic Component

Overall, approximately 5–10% of breast cancers are attributable to gene mutations.³ The most common cause of hereditary breast cancer is an inherited mutation in the BRCA1 or BRCA2 gene.³ These mutations significantly increase risk: 7 out of 10 women with a BRCA1 or BRCA2 gene mutation develop breast cancer by the age of 80.³ The implications for early detection are described in the "Early Detection and Screening" section.

 

Symptoms

Most patients experience no symptoms when the cancer is still at an early stage — which is why early detection is so important.⁸
At advanced stages, breast cancer can cause various signs:8,9

  • Palpable changes — hard, spherical lumps or indurations in the breast or under the arm
  • Visible changes — changes in size, shape or colour of the breast; skin changes such as dimpling, rash or redness, particularly around the nipple
  • Discharge — abnormal or bloody fluid from the nipple
    General symptoms — unintentional weight loss

Over time, cancer cells can spread to other organs such as the lungs, liver, brain and bones. As a result, new cancer-related symptoms such as bone pain or headaches may occur.⁸

Early Detection and Screening

Because breast cancer usually causes no symptoms at an early stage, systematic early detection plays a central role.8,10


Recommendations for women at average risk
Systematic early detection through breast cancer screening programmes can help discover the disease at a stage when the chances of cure are highest.10

For women at average risk aged 50–69, regular mammography screening every 2 years is recommended.10,14

 

Recommendations for women at increased risk
For those with an increased familial risk, international guidelines recommend genetic assessment and — if a hereditary predisposition is confirmed — intensified screening with breast MRI from the age of 30 (or 5 years before the youngest affected family member), at annual intervals; for BRCA1 carriers, screening every six months is recommended.10,12

Diagnosis

Diagnosis is based on clinical examination combined with imaging, which should include bilateral diagnostic mammography and ultrasound of both breasts and regional lymph nodes.¹⁰ MRI is recommended in cases of uncertainty after standard imaging and in specific clinical situations (e.g. familial breast cancer associated with BRCA1/2 mutations, lobular carcinomas, suspected multifocal and/or multicentric breast cancer).¹⁰

Diagnosis is confirmed by biopsy and pathological examination.¹⁰ The examination should include histological type, grade and immunohistochemical analysis of oestrogen receptor, progesterone receptor and HER2 receptor status, as well as a proliferation marker such as Ki-67 (a laboratory test that determines tumour growth behaviour).¹⁰

Investigation for distant metastases (bone, liver and lungs) is recommended only for patients with stage IIb or higher, patients with a high risk of recurrence at initial diagnosis, and/or symptomatic patients.¹⁰

Treatment

Treatment options for breast cancer include surgery, radiotherapy and systemic drug therapy.¹¹ Treatment decisions should be based on an individual risk-benefit analysis that takes into account patient and tumour characteristics, comorbidities and patient preferences.¹¹

Breast-conserving surgery (usually with postoperative radiotherapy) is an appropriate surgical option for most patients with breast cancer.¹¹ Patients with hormone receptor-positive invasive tumours should receive endocrine therapy (unless contraindicated).¹¹ For patients with HER2-positive breast cancer, adjuvant treatment with HER2-targeted therapy (plus chemotherapy) is recommended.¹¹ In triple-negative breast cancer (TNBC), neither hormonal nor HER2-targeted therapies are available. Treatment relies on chemotherapy, which in eligible patients may be supplemented by immunotherapy or targeted approaches in the presence of a confirmed BRCA mutation.11

Abbreviations

BRCA1/2: Breast cancer 1/2 · HER2: human epidermal growth factor receptor 2 · MRI: magnetic resonance imaging

 

References:

 

  1. Bray F, et al. Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin. 2024 May-Jun;74(3):229-263.
  2. Krebs in der Schweiz: wichtige Zahlen; Krebsliga Schweiz, as of November 2025, available online at: https://www.krebsliga.ch/ueber-krebs/zahlen-fakten. Last accessed: 27.05.2026
  3. Feng Y, et al. Breast cancer development and progression: Risk factors, cancer stem cells, signaling pathways, genomics, and molecular pathogenesis. Genes Dis. 2018 May 12;5(2):77-106.
  4. Bundesamt für Statistik. Krebs: Anzahl und Rate der Neuerkrankungen und Todesfälle nach Sprachregion, Krebsart, Geschlecht, Periode und Altersklasse. Published on: 10.11.2025. Available online at: https://www.bfs.admin.ch/bfs/de/home/statistiken/gesundheit/gesundheitszustand/krankheiten/krebs.assetdetail.36138872.html. Last accessed: 27.05.2026
  5. Deutsche Krebsgesellschaft. Brustkrebs – Ursachen und Risikofaktoren. As of: 31.05.2022. Available online at: https://www.krebsgesellschaft.de/onko-internetportal/basis-informationen-krebs/krebsarten/brustkrebs/ursachen-und-risikofaktoren.html. Last accessed: 27.05.2026.
  6. Fragomeni SM, et al. Molecular Subtypes and Local-Regional Control of Breast Cancer. Surg Oncol Clin N Am. 2018 Jan;27(1):95-120.
  7. Rinnerthaler G, et al. HER2 Directed Antibody-Drug-Conjugates beyond T-DM1 in Breast Cancer. Int J Mol Sci. 2019 Mar 5;20(5):1115.
  8. Breast cancer, Factsheet, WHO. As of 16 April 2026. Available online at: https://www.who.int/news-room/fact-sheets/detail/breast-cancer. Last accessed: 27.05.2026
  9. Krebsliga Schweiz. Brustkrebs (Mammakarzinom). As of Dec 2024. Available online at: https://www.krebsliga.ch/ueber-krebs/krebsarten/brustkrebs. Last accessed: 27.05.2026
  10. Loibl S, et al. Early breast cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up. Ann Oncol. 2024 Feb;35(2):159-182.
  11. ESMO Guidelines Committee, Metastatic breast cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up†, Annals of Oncology (2026), doi: https://doi.org/10.1016/j.annonc.2026.05.707.
  12. Sessa C, et al. Risk reduction and screening of cancer in hereditary breast-ovarian cancer syndromes: ESMO Clinical Practice Guideline. Ann Oncol. 2023 Jan;34(1):33-47.
  13. Karch André et al. Evaluation der Brustkrebsmortalität im Deutschen Mammographie‐Screening‐Programm, Ressortforschungsberichte zum Strahlenschutz, Vorhaben 3621S42410, Bundesamt für Strahlenschutz, Juli 2025 online: BfS - Abgeschlossene Forschungsvorhaben - Evaluation der Brustkrebsmortalität im Deutschen Mammographie‐Screening‐Programm. Last accessed: 27.05.2026
  14. Krebsliga Schweiz. Früherkennung von Brustkrebs. As of Oct. 2025. Available online at: https://www.krebsliga.ch/ueber-krebs/frueherkennung/brustkrebs. Last accessed: 27.05.2026

 

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CH-12902 05/2026

 

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