Breast Cancer

What breast cancer is

The breast is made of lobules (milk glands), ducts that carry milk to the nipple, and fatty and fibrous tissue. Breast cancer develops when cells in the ducts or lobules grow uncontrollably, usually because of accumulated DNA changes.

• Non-invasive (in situ): cancer cells stay inside the duct. Ductal carcinoma in situ (DCIS) is stage 0 and is often found on mammograms.
• Invasive: cancer cells break out into surrounding breast tissue and can spread through lymph vessels and blood to lymph nodes, bones, liver, lungs or brain.

Signs and symptoms of breast cancer

Many breast cancers are found on screening mammograms before symptoms. When symptoms occur, they include:

• a new lump or thickening in the breast or armpit, often hard, irregular and painless, but some are tender
• dimpling, puckering or orange-peel texture of the skin
• redness, warmth or swelling of the breast
• a nipple that turns inward, changes shape, or develops a scaly rash
• nipple discharge, especially bloody or from one duct
• a change in the size or shape of one breast
• swelling in the armpit or above the collarbone

Most breast lumps are not cancer. Cysts, fibrocystic changes and fibroadenomas are much more common, especially before menopause. But every new lump should be checked. See breast lump.

Inflammatory breast cancer

A rare, fast-growing type that causes redness, swelling and warmth over a large part of the breast, often with orange-peel skin, and usually no distinct lump. It can be mistaken for infection; if a presumed breast infection does not improve within a week of antibiotics, ask about a biopsy.

Breast cancer in men

Men have a small amount of breast tissue and can develop breast cancer, usually as a painless lump behind the nipple. Risks include older age, BRCA2 mutations, Klinefelter syndrome and high estrogen levels.

Types of breast cancer

By where it starts

• Invasive ductal carcinoma: about 70 to 80 percent of invasive breast cancers. See invasive ductal carcinoma.
• Invasive lobular carcinoma: about 10 to 15 percent; may not form a distinct lump and can be harder to see on mammograms. See lobular carcinoma.
• Rarer types: inflammatory, Paget disease of the nipple, metaplastic and others.

By biology (the most important for treatment)

Tumor grade (how abnormal the cells look) and genomic tests that predict recurrence risk also guide treatment.

Risk factors

Risks you cannot change

• Being female and getting older: most breast cancers occur after 50.
• Inherited gene changes: BRCA1 and BRCA2 mutations greatly raise lifetime risk; PALB2, TP53, CHEK2, ATM and others also increase risk. About 5 to 10 percent of breast cancers are hereditary.
• Family history of breast or ovarian cancer, especially in close relatives diagnosed young.
• Dense breast tissue on mammograms.
• Early periods, late menopause.
• Previous breast cancer or certain benign breast conditions (atypical hyperplasia, LCIS).
• Chest radiation at a young age, for example for Hodgkin lymphoma.

Risks you can influence

• alcohol: risk rises with each daily drink
• excess weight after menopause
• physical inactivity
• combined hormone therapy after menopause, especially long-term
• having no children or a first child after 30, and not breastfeeding

Screening

Screening mammograms find cancers before they can be felt, when treatment is most successful.

• Average-risk women: the US Preventive Services Task Force recommends a mammogram every 2 years from age 40 to 74. Some organizations advise yearly screening.
• Higher-risk women (BRCA carriers, strong family history, chest radiation before 30) may start earlier and add yearly breast MRI.
• Dense breasts: you may be offered additional ultrasound or MRI; discuss with your doctor.
• Breast awareness: know how your breasts normally look and feel, and report changes promptly.

Diagnosis

1. Clinical breast exam.
2. Diagnostic mammogram and ultrasound of the area of concern.
3. Core needle biopsy: the key test, taking small samples for the pathologist.
4. Receptor testing on the biopsy: estrogen receptor, progesterone receptor and HER2.
5. Breast MRI in selected cases, such as lobular cancer or high-risk patients.
6. Staging tests for larger or node-positive cancers: CT, bone scan or PET scan.
7. Genetic testing for people with strong family history, young age at diagnosis, triple-negative cancer, male breast cancer or Ashkenazi Jewish ancestry.

Stages of breast cancer

Modern staging also includes grade, receptor status and genomic scores, which can raise or lower the stage. Survival figures are averages from past years; today's treatments are often better.

Treatment

Treatment is planned by a multidisciplinary team and tailored to the subtype, stage, your age, genetics and preferences.

Surgery

• Lumpectomy (breast-conserving surgery) followed by radiation, which is as effective as mastectomy for most early cancers.
• Mastectomy: removal of the whole breast, sometimes both in high-risk carriers, with options for breast reconstruction.
• Sentinel lymph node biopsy to check the first armpit nodes; full node removal is now needed less often.

Radiation therapy

After lumpectomy, and after mastectomy in higher-risk cases, to reduce the chance of the cancer returning. Courses are increasingly short, sometimes 1 to 3 weeks.

Systemic (whole-body) treatments

• Hormone therapy: tamoxifen or aromatase inhibitors (anastrozole, letrozole, exemestane) for 5 to 10 years for hormone receptor-positive cancer; ovarian suppression in some premenopausal women.
• Chemotherapy: before surgery (neoadjuvant) to shrink tumors, or after surgery (adjuvant).
• Targeted therapy: HER2-targeted drugs, CDK4/6 inhibitors, PARP inhibitors for BRCA carriers, antibody-drug conjugates.
• Immunotherapy: for some triple-negative breast cancers.

Metastatic breast cancer

Stage IV breast cancer is usually not curable but is increasingly treatable as a long-term condition, with sequences of hormone, targeted and chemotherapy treatments, plus radiation or surgery for specific sites and good symptom control.

Side effects and life after treatment

Common effects include fatigue, hair loss with some chemotherapy, early menopause symptoms, joint aches with aromatase inhibitors, and lymphedema (arm swelling) after node surgery or radiation. Survivorship care includes regular checkups, yearly mammograms of remaining breast tissue, bone health monitoring, exercise and emotional support.

Prevention and risk reduction

• Limit alcohol, keep a healthy weight and stay active.
• Breastfeed if possible.
• Discuss the risks of menopausal hormone therapy.
• For high-risk women: risk-reducing medicines (tamoxifen, raloxifene or aromatase inhibitors), enhanced screening, and in BRCA carriers, consideration of risk-reducing surgery.

Frequently asked questions

What are the early signs of breast cancer?

The most common early sign is a new lump or thickening, often painless. Other signs include skin dimpling, redness, a nipple turning inward, nipple discharge, a rash on the nipple, swelling in the armpit, and a change in breast size or shape. Many early cancers cause no symptoms and are found on mammograms.

Is breast cancer painful?

Usually not at first. Most breast cancer lumps are painless, although some are tender. Breast pain alone, especially if it varies with your cycle and affects both breasts, is rarely due to cancer. Persistent pain in one spot should still be checked.

At what age should I start getting mammograms?

US guidelines recommend average-risk women start screening mammograms at age 40, every 2 years until 74, though some groups advise yearly. Women at higher risk, such as BRCA carriers, may start earlier and add breast MRI. Discuss your personal risk with your doctor.

Can men get breast cancer?

Yes. About 1 percent of breast cancers occur in men, usually over 60. The most common sign is a painless lump behind the nipple, sometimes with nipple changes or discharge. Men with BRCA2 mutations have a higher risk. Treatment is similar to that for women.

What is the survival rate for breast cancer?

Overall 5-year relative survival in the US is about 91 percent. It is about 99 percent when cancer is confined to the breast, about 86 percent when it has spread to nearby lymph nodes, and about 32 percent when it has spread to distant organs. Outcomes continue to improve.

Does a family history mean I will get breast cancer?

No. Most people with a family history never develop breast cancer, and most people who do have no affected relatives. A strong family history, especially of young-onset breast or ovarian cancer, may mean genetic counseling, testing and earlier or more intensive screening.