breast cancer

breast cancer
Name	Breast cancer
Caption	A mammogram showing a suspicious mass.
Field	Oncology, Surgery
Symptoms	Lump, skin changes, nipple discharge
Complications	Metastasis, lymphedema
Risks	BRCA mutation, hormone replacement therapy, obesity
Diagnosis	Biopsy, mammography, ultrasound
Treatment	Surgery, radiation therapy, chemotherapy, hormonal therapy, targeted therapy
Prognosis	Varies by stage; 5-year survival >90% for localized disease
Frequency	~2.3 million new cases globally (2020)
Deaths	~685,000 globally (2020)

breast cancer. It is a malignant tumor that originates in the cells of the breast, primarily in the milk ducts or lobules. The disease is a major global health concern, leading to significant morbidity and mortality worldwide. Advancements in screening and treatment have substantially improved outcomes over recent decades.

Signs and symptoms

The most common initial sign is a new lump or mass, often detected through breast self-examination or clinical breast examination. Other presentations can include changes in breast size or shape, skin dimpling (often described as "peau d'orange"), and nipple retraction. Symptoms may also involve nipple discharge, particularly if it is bloody, or persistent breast pain unrelated to the menstrual cycle. In more advanced cases, signs can involve ulceration of the skin or symptoms related to distant metastasis, such as bone pain or shortness of breath.

Risk factors

Major non-modifiable risk factors include female sex, increasing age, and a strong family history, particularly associated with inherited mutations in genes like BRCA1 and BRCA2. Reproductive factors that increase lifetime estrogen exposure, such as early menarche, late menopause, and nulliparity, are also significant. Modifiable lifestyle risks encompass obesity in postmenopausal women, alcohol consumption, and physical inactivity. Exogenous hormone use, particularly combined estrogen-progestogen therapy, and exposure to ionizing radiation, especially during adolescence, are well-established environmental risks.

Pathophysiology

The disease fundamentally involves the uncontrolled proliferation of epithelial cells lining the ducts or lobules of the breast. This is driven by an accumulation of genetic mutations and epigenetic alterations that activate oncogenes like HER2/neu and inactivate tumor suppressor genes such as TP53. The estrogen receptor and progesterone receptor pathways are critical in the growth of many tumors, providing targets for endocrine therapy. The process of local invasion is facilitated by the degradation of the basement membrane and the extracellular matrix, while metastasis typically occurs via the lymphatic system to axillary lymph nodes or hematogenously to sites like bone, lung, liver, and brain.

Diagnosis

Diagnosis begins with imaging, most commonly mammography, often employed in organized screening programs like those promoted by the American Cancer Society. Suspicious findings are further evaluated with breast ultrasound or MRI. A definitive diagnosis requires a tissue biopsy, such as a core needle biopsy, to obtain a histopathology sample. The biopsy material is analyzed to confirm malignancy, determine the histologic type (e.g., ductal carcinoma in situ), and assess critical biomarkers including hormone receptor status and HER2 expression, which are essential for treatment planning. Staging follows, typically using the TNM classification system from the American Joint Committee on Cancer.

Treatment

Management is multidisciplinary, tailored to the tumor stage, subtype, and patient preference. Surgery remains a cornerstone, ranging from breast-conserving surgery (lumpectomy) to mastectomy, often with sentinel lymph node biopsy or axillary lymph node dissection. Adjuvant therapy is frequently administered post-surgery and may include radiation therapy to the breast or chest wall. Systemic treatments include chemotherapy (e.g., anthracyclines, taxanes), endocrine therapy (e.g., tamoxifen, aromatase inhibitors) for hormone receptor-positive disease, and targeted therapies like trastuzumab for HER2-positive tumors. For advanced or metastatic disease, treatment focuses on palliative care and controlling progression.

Prognosis

Prognosis is highly dependent on the stage at diagnosis, with excellent survival rates for localized disease. Key prognostic factors include tumor size, nodal status, histologic grade, and the presence of lymphovascular invasion. Biomarker status profoundly influences outcomes; hormone receptor-positive cancers generally have a more favorable prognosis, while triple-negative breast cancer is associated with a higher risk of early recurrence. Long-term follow-up is essential to monitor for late effects of treatment, such as cardiotoxicity from certain therapies, and the risk of contralateral breast cancer.

Epidemiology

It is the most commonly diagnosed cancer globally among women, with incidence rates varying significantly by geographic region; higher rates are typically observed in North America and Western Europe, partly due to widespread screening mammography. Incidence has been rising in many transitional economies, including parts of Asia and Africa, linked to changes in reproductive patterns and lifestyle factors. While mortality rates have declined in high-income countries due to early detection and improved therapies, it remains a leading cause of cancer death in women worldwide, with a disproportionate burden in less developed regions where access to timely diagnosis and treatment is limited.

Category:Breast cancer Category:Oncology Category:Women's health