Breast cancer develops when abnormal cells grow in breast tissue. It’s the second most common cancer in women in the U.S., after skin cancer. Early detection has significantly improved survival rates.
Common Symptoms
Breast cancer isn’t always obvious, but symptoms can include:
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A lump in the breast
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Bloody nipple discharge
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Changes in breast size, shape, or appearance
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Skin changes, such as dimpling, redness, or thickening
Regular self-exams and mammograms are key to catching changes early. Still, some breast cancers cause no symptoms at all.
How Breast Cancer Spreads
Cancer cells can move through the lymphatic system and settle in new areas of the body:
Direct Tissue Spread: Cancer grows from the breast into the nearby chest wall.
Lymphatic Spread: Cancer cells travel through lymph nodes and into other tissues.
When cancer spreads beyond the breast, it’s called metastasis. The most common distant sites include:
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Bones
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Brain
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Liver
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Lungs
Diagnosing Metastasis
Doctors typically order testing only when symptoms or tumor characteristics suggest cancer may have spread. Options include:
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Chest X-ray
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Bone scan
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CT scan
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MRI
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Ultrasound
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PET scan
The choice depends on symptoms and medical history. These tests are noninvasive and usually don’t require a hospital stay. You may receive special prep instructions, such as taking oral contrast before a CT scan.
How Breast Cancer Is Staged
Staging helps determine treatment and outlook. The American Cancer Society uses two main staging approaches:
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Pathologic stage: Based on tissue removed during surgery
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Clinical stage: Used when surgery isn’t possible; based on exams, imaging, and biopsy
Two staging perspectives are used:
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Anatomic staging: Tumor size and lymph node involvement
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Prognostic staging: Five-year survival expectations based on tumor biology and risk factors
Your doctor determines the stage by evaluating:
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Whether the cancer is invasive
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Tumor size
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Lymph node involvement
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Spread to other body areas
Stages of Breast Cancer
Stage 0
Noninvasive. Includes ductal carcinoma in situ (DCIS) and certain precancerous lesions. Highly treatable.
Stage 1
Invasive but localized. Tumor is under 2 cm with no lymph node involvement. Very treatable.
Stage 2
Invasive, divided into 2A and 2B:
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May involve lymph nodes or larger tumors (2–5 cm)
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Tumor may be over 5 cm with no lymph node spread
Still highly treatable but may require more aggressive therapy.
Stage 3
Invasive and locally advanced but not spread to distant organs. Subdivided into 3A, 3B, and 3C:
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May involve more lymph nodes (4–10+)
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May spread to breastbone, skin, or chest wall
Stage 4
Metastatic. Cancer has spread to distant organs such as the brain, bones, lungs, or liver. No longer curable, but still treatable.
