Breast cancer develops when abnormal cells in breast tissue grow uncontrollably. It occurs mainly in women but can also occur in men. Earlier detection can expand treatment options, although symptoms and prognosis vary by cancer type and stage.
Possible symptoms
- A new breast or underarm lump
- Change in breast size or shape
- Skin dimpling, thickening or persistent redness
- New nipple inversion
- Nipple discharge, particularly if bloody
- Persistent focal breast or nipple changes
Most breast changes are not cancer, but a new or persistent change should be assessed.
Diagnosis
Assessment may include clinical examination, mammography, ultrasound or MRI. A biopsy is used to determine whether suspicious tissue is cancerous and to identify tumor characteristics that guide treatment.
Treatment
Treatment may include breast-conserving surgery or mastectomy, radiation therapy, chemotherapy, hormone therapy, targeted medicines and immunotherapy. The plan depends on cancer stage, tumor biology, overall health and patient preferences.
Screening
Mammography can detect some breast cancers before symptoms develop. Screening recommendations vary according to age, individual risk and national guidance. People with strong family histories or certain inherited genetic variants may need individualized surveillance.
Related topics
Sources and further reading
Last reviewed: 4 September 2026. This page provides general health information and does not replace individual medical assessment or treatment.