One in eight women in the United States will be diagnosed with breast cancer in her lifetime, making it the most commonly diagnosed cancer among American women after skin cancer. In 2024, the American Cancer Society estimated approximately 310,720 new cases of invasive breast cancer and 42,250 deaths. Behind these statistics is both a sobering reality and genuine cause for hope — 5-year survival rates exceed 90 percent overall, and when detected at a localized stage, that figure rises to 99 percent. Understanding your personal risk, following screening guidelines, and knowing what treatment advances are available can make a critical difference. For an overview of major health conditions, see our medical conditions guide.
Types of Breast Cancer
Breast cancer is not a single disease but a group of diseases classified by where they originate, whether they’ve spread beyond their site of origin, and their molecular characteristics. The two broadest categories are non-invasive (in situ) and invasive breast cancer.
Non-Invasive Breast Cancer
Ductal carcinoma in situ (DCIS) is the most common non-invasive type. Abnormal cells are confined to the milk ducts and have not penetrated into surrounding breast tissue. DCIS accounts for approximately 20 percent of breast cancers detected through screening. It is considered stage 0 and has an excellent prognosis, though it is treated to prevent potential progression to invasive cancer. Lobular carcinoma in situ (LCIS) is not considered a true cancer but rather a marker of increased breast cancer risk.
Invasive Breast Cancer
Invasive ductal carcinoma (IDC) is the most common type, accounting for 70 to 80 percent of all invasive breast cancers. It starts in the milk ducts and invades surrounding breast tissue. Invasive lobular carcinoma (ILC) accounts for approximately 10 to 15 percent and begins in the lobules (milk-producing glands). ILC tends to be harder to detect on mammography because it often does not form a distinct mass. Less common types include inflammatory breast cancer (aggressive, causing redness and swelling), Paget disease of the nipple, and phyllodes tumors.
Molecular Subtypes
Modern breast cancer treatment is guided by molecular profiling, which classifies tumors based on receptor status. According to the National Cancer Institute, the key markers are estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Hormone receptor-positive (HR+) cancers account for about 70 percent of cases and are driven by hormones. HER2-positive cancers (15 to 20 percent) overproduce the HER2 protein, making them susceptible to HER2-targeted drugs. Triple-negative breast cancer (TNBC) — lacking ER, PR, and HER2 — accounts for 10 to 15 percent and historically had fewer targeted treatment options, though immunotherapy and antibody-drug conjugates have expanded the arsenal.
Risk Factors
Being female and getting older are the two strongest risk factors for breast cancer. Approximately 99 percent of breast cancers occur in women, though men can develop breast cancer too (about 2,800 cases annually in the U.S.). The median age at diagnosis is 62.
Genetic factors play a significant role. Mutations in the BRCA1 and BRCA2 genes account for 5 to 10 percent of breast cancers and carry a lifetime risk of 45 to 72 percent. Other high-penetrance genes include PALB2, TP53, PTEN, and CDH1. Family history matters even without an identified mutation — having one first-degree relative with breast cancer approximately doubles your risk. The USPSTF recommends genetic counseling and potential BRCA testing for women whose personal or family history suggests an increased risk of harmful mutations.
Hormonal and reproductive factors influence risk: early menstruation (before age 12), late menopause (after 55), first pregnancy after age 30, never having been pregnant, and hormone replacement therapy (particularly combined estrogen-progestin therapy) all modestly increase risk. Modifiable risk factors include excess alcohol consumption (risk increases approximately 7 to 10 percent per drink per day), obesity (particularly after menopause, when fat tissue becomes a primary estrogen source), physical inactivity, and prior chest radiation (e.g., for Hodgkin lymphoma in young adulthood).
Symptoms and Early Detection
The most common presenting symptom of breast cancer is a painless lump or mass in the breast. According to the Mayo Clinic, other signs include thickening or swelling of part of the breast, skin dimpling or puckering, redness or flaky skin on the breast or nipple, nipple inversion (pulling inward), nipple discharge other than breast milk (especially if bloody), any change in breast size or shape, and pain in any area of the breast that doesn’t resolve.
Inflammatory breast cancer deserves special mention because it presents differently — the breast may appear red, swollen, warm, and have a texture resembling an orange peel (peau d’orange) without a distinct lump. This aggressive subtype can be mistaken for a breast infection, delaying diagnosis.
Breast self-awareness — being familiar with the normal look and feel of your breasts so you notice changes — is recommended by major cancer organizations. While formal monthly self-exams are no longer universally recommended due to high false-positive rates and lack of mortality benefit, promptly reporting any new breast changes to your doctor remains important.
Screening Guidelines
Screening mammography has been shown to reduce breast cancer mortality by detecting cancers before they become symptomatic. Guidelines vary somewhat among organizations, reflecting different weighting of benefits versus harms (false positives, unnecessary biopsies, overdiagnosis).
The USPSTF updated its recommendation in 2024 to advise biennial screening mammography for all women beginning at age 40 and continuing through age 74. The American Cancer Society recommends annual mammography beginning at age 45 (with the option to start at 40), transitioning to biennial screening at age 55. The American College of Radiology recommends annual screening starting at age 40.
For women at higher-than-average risk — including BRCA mutation carriers, those with a strong family history, or those who received chest radiation before age 30 — enhanced screening with breast MRI in addition to mammography is recommended, often beginning at age 25 to 30. Risk assessment tools like the Tyrer-Cuzick model can help determine whether enhanced screening is appropriate for individual patients.
Dense breast tissue, which is present in approximately 40 percent of women, both increases breast cancer risk and reduces mammographic sensitivity. Many states now require notification of breast density on mammography reports. Supplemental screening with breast ultrasound or MRI may be considered for women with dense breasts, though optimal screening strategies for this population are still being refined. Understanding insurance coverage for screening can help remove financial barriers.
Diagnosis and Staging
When an abnormality is detected on screening or physical examination, diagnostic workup follows a structured approach. Diagnostic mammography provides additional targeted images. Ultrasound helps characterize masses — distinguishing solid from cystic lesions — and is the preferred initial imaging for women under 30. Breast MRI provides the most sensitive assessment but is not used as a first-line diagnostic tool due to its high false-positive rate and cost.
Tissue diagnosis through biopsy is required before any treatment. Core needle biopsy, performed under image guidance (ultrasound or stereotactic), is the standard initial biopsy technique. It provides sufficient tissue for histologic diagnosis and receptor testing. Surgical (excisional) biopsy is reserved for cases where core biopsy is technically difficult or yields inconclusive results.
Staging involves assessing the tumor size, lymph node involvement, and presence of distant metastases using the TNM system. Imaging studies may include chest CT, bone scan, PET-CT, and brain MRI depending on the clinical scenario. The American Cancer Society reports the following 5-year relative survival rates by stage: localized (stage I/II) — 99 percent; regional (stage III) — 87 percent; distant (stage IV) — 31 percent.
Treatment Options
Surgery
Surgical options include breast-conserving surgery (lumpectomy, removing the tumor with a margin of normal tissue) and mastectomy (removal of the entire breast). Multiple randomized trials have demonstrated equivalent survival between lumpectomy plus radiation and mastectomy for early-stage cancers. The choice depends on tumor size relative to breast size, number and location of tumors, patient preference, and ability to receive radiation therapy.
Sentinel lymph node biopsy — removing only the first one or two lymph nodes to which a breast cancer would drain — has largely replaced full axillary lymph node dissection for clinically node-negative patients, reducing the risk of lymphedema and other complications. Breast reconstruction, either immediate or delayed, using implants or autologous tissue, is an option for women undergoing mastectomy.
Radiation Therapy
Radiation is standard after breast-conserving surgery, reducing local recurrence by approximately two-thirds. It may also be recommended after mastectomy for larger tumors or positive lymph nodes. Hypofractionated whole-breast radiation (shorter, more intense treatment delivered over 3 to 4 weeks rather than 5 to 6) has become the new standard based on trials showing equivalent outcomes with greater convenience.
Systemic Therapy
Systemic therapy — chemotherapy, hormone therapy, targeted therapy, and immunotherapy — is tailored to the molecular subtype. HR-positive cancers are treated with endocrine therapy: tamoxifen for premenopausal women and aromatase inhibitors (anastrozole, letrozole, exemestane) for postmenopausal women, typically for 5 to 10 years. CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib) added to endocrine therapy have significantly improved outcomes for HR-positive metastatic breast cancer.
HER2-positive cancers are treated with HER2-targeted agents — trastuzumab (Herceptin) revolutionized HER2-positive breast cancer treatment, and newer agents like pertuzumab, T-DM1, and trastuzumab deruxtecan have further improved outcomes. According to the National Cancer Institute, the prognosis for HER2-positive breast cancer has improved dramatically since the introduction of targeted therapy.
For triple-negative breast cancer, chemotherapy remains the backbone of treatment, but pembrolizumab (immunotherapy) combined with chemotherapy is now standard for early-stage and advanced TNBC with PD-L1 expression. Antibody-drug conjugates like sacituzumab govitecan have added another option for metastatic TNBC. Genomic tests such as Oncotype DX and MammaPrint help identify which patients with HR-positive, node-negative cancer benefit from chemotherapy versus endocrine therapy alone.
Survivorship and Quality of Life
There are more than 4 million breast cancer survivors in the United States — a testament to improved treatment but also a reminder that survivorship brings its own challenges. Long-term and late effects of treatment can include lymphedema, cardiac effects from certain chemotherapy drugs and radiation, bone loss from aromatase inhibitors, menopausal symptoms, cognitive changes (“chemo brain”), fatigue, and emotional distress including anxiety about recurrence.
Survivorship care plans, recommended by the American Society of Clinical Oncology, outline treatment history, surveillance schedules, and management of long-term effects. Regular follow-up typically includes clinical examinations every 3 to 6 months for the first 3 years, then annually, plus annual mammography of the preserved and/or contralateral breast. Routine use of advanced imaging or blood tumor markers for surveillance is not recommended for asymptomatic survivors.
Exercise has been shown in multiple studies to reduce fatigue, improve mood, lower recurrence risk, and improve overall survival in breast cancer survivors. The American Cancer Society recommends at least 150 minutes of moderate or 75 minutes of vigorous physical activity per week for cancer survivors.
Frequently Asked Questions
Can men get breast cancer?
Yes. While rare, approximately 2,800 men are diagnosed with breast cancer annually in the United States. Male breast cancer is usually detected as a painless lump beneath the nipple. Risk factors include older age, family history (particularly BRCA2 mutations), obesity, Klinefelter syndrome, and liver disease. Treatment parallels that for women and typically includes surgery, and when indicated, radiation, chemotherapy, and hormone therapy. Outcomes stage-for-stage are comparable to those in women.
Does wearing an underwire bra cause breast cancer?
No. This is a persistent myth with no scientific evidence to support it. The American Cancer Society and other medical organizations have stated that bra type, tightness, or underwire does not increase breast cancer risk. This claim originated from a non-peer-reviewed book and has been debunked by multiple studies.
What does a breast cancer lump feel like?
Breast cancer lumps are often hard, irregular in shape, and painless, though they can vary in presentation. Some feel rounded and firm. Inflammatory breast cancer may not produce a lump at all. Normal breast tissue can feel lumpy, particularly before menstruation, which is why knowing your baseline is important. Any new lump or mass that persists through a menstrual cycle, feels distinctly different from surrounding tissue, or is progressively growing should be evaluated by your doctor.
How effective is mammography at detecting breast cancer?
Mammography detects approximately 84 to 87 percent of breast cancers in women who are screened. Sensitivity is higher in women with fatty breast tissue and lower in women with dense breast tissue (approximately 48 to 64 percent sensitivity). 3D mammography (tomosynthesis) improves detection rates by 27 to 40 percent compared to 2D mammography alone and is increasingly used as the standard screening tool. For high-risk women, the addition of breast MRI increases sensitivity to over 95 percent.
Should I get genetic testing for breast cancer?
Genetic counseling and testing are recommended if you have a strong family history of breast or ovarian cancer, a family member with a known gene mutation, breast cancer diagnosed before age 50, triple-negative breast cancer, bilateral breast cancer, or if you are of Ashkenazi Jewish descent (who have higher rates of BRCA mutations). Your doctor or a genetic counselor can perform a risk assessment and determine whether testing is appropriate for your specific situation.
Taking Charge of Your Breast Health
Regardless of your risk level, proactive steps make a difference. Start screening mammography by age 40 — don’t wait for a doctor to bring it up. If you have a family history that concerns you, seek a formal risk assessment. Many breast cancer centers offer high-risk clinics that provide personalized screening and prevention plans.
Modifiable risk factors matter too. Maintaining a healthy weight (particularly after menopause), staying physically active, moderating alcohol intake, and discussing the risks and benefits of hormone replacement therapy with your doctor are all evidence-based strategies. For very high-risk women, risk-reducing medications (tamoxifen, raloxifene, or aromatase inhibitors) can reduce breast cancer risk by 30 to 50 percent, and risk-reducing mastectomy is an option for BRCA carriers.
If you’re diagnosed with breast cancer, seek care from a multidisciplinary team at a center experienced in breast cancer treatment. Ask about your tumor’s molecular profile — it directly determines which treatments will be most effective. Explore clinical trials if appropriate. And remember that breast cancer treatment has never been more effective or more personalized than it is today.