Breast Cancer: Types, Risk Factors, Symptoms, Diagnosis, Treatment and Prevention

Breast cancer starts in breast tissue, when cells in the breast change and grow out of control: new cells form when they aren't needed, and old cells don't die when they should. The extra cells can form a mass — a tumor.

• In situ: the cancer has not spread further.
• Invasive: it has spread outside the breast — perhaps only to nearby tissue and lymph nodes, or, through the lymph system or blood, to other parts of the body (metastasis).

It is the second most common cancer in women in the United States, and it can rarely affect men.

Types

The type depends on which breast cells become cancerous:

Causes

Breast cancer comes from changes in genetic material (DNA). Often the cause of those changes is unknown; sometimes they are inherited — present from birth — and the cancer is called hereditary breast cancer. Changes in the BRCA1 and BRCA2 genes raise the risk of breast cancer, and of ovarian and other cancers. Lifestyle and environment matter too.

Risk factors

• older age;
• a history of breast cancer or of benign (noncancerous) breast disease;
• inherited risk, including BRCA1 and BRCA2 changes;
• dense breast tissue;
• a reproductive history with more exposure to estrogen: periods starting early, giving birth first at an older age or never, menopause starting late;
• hormone therapy for menopause;
• radiation therapy to the breast or chest;
• obesity;
• drinking alcohol.

Signs and symptoms

• a new lump or thickening in or near the breast or in the armpit;
• a change in the breast's size or shape;
• a dimple or puckering in the breast's skin — it can look like orange peel;
• a nipple turned inward;
• nipple discharge other than breast milk — especially if sudden, bloody or from one breast only;
• scaly, red or swollen skin on the nipple area or breast;
• pain in any part of the breast.

Diagnosis

Finding it:

• a physical exam, including a clinical breast exam (CBE) of the breasts and armpits for lumps or anything unusual;
• a medical history;
• imaging: mammogram, ultrasound or MRI;
• a breast biopsy;
• blood chemistry tests of electrolytes, fats, proteins, glucose and enzymes — such as a basic metabolic panel (BMP), a comprehensive metabolic panel (CMP) or an electrolyte panel.

Studying the cancer cells, to choose treatment:

• genetic tests for changes such as in the BRCA and TP53 genes;
• a HER2 test — HER2 is a growth-related protein on the outside of all breast cells; cancer cells with more HER2 than normal can grow and spread faster;
• an estrogen and progesterone receptor test — cancers with more receptors than normal are receptor-positive, and may grow faster.

Staging finds whether the cancer has spread within the breast or elsewhere, using more imaging and a sentinel lymph node biopsy, which checks whether it has reached the lymph nodes.

Treatment

• Surgery: a mastectomy removes the whole breast; a lumpectomy removes the cancer and some normal tissue around it, but not the breast.
• Radiation therapy.
• Chemotherapy.
• Hormone therapy, which blocks cancer cells from the hormones they need to grow.
• Targeted therapy: drugs or other substances that attack specific cancer cells with less harm to normal cells.
• Immunotherapy.

Prevention

Healthy habits may help:

• stay at a healthy weight;
• limit alcohol;
• get enough exercise;
• limit estrogen exposure — breastfeed if you can, and limit hormone therapy.

People at high risk may be offered medicines that lower it; some women at very high risk choose to have healthy breasts removed (mastectomy) to prevent cancer. Regular mammograms matter too: they can find cancer early, when it is easier to treat.

Sources

Based on "Breast Cancer," MedlinePlus, National Library of Medicine, drawing on the National Cancer Institute; a work of the United States government in the public domain. The source spells menopause "meopause" once; corrected here.