When a breast change or abnormal screening result is found, the next step is diagnosis. A clear diagnosis helps guide the right treatment plan.

How breast cancer is diagnosed

1. Clinical breast exam

A doctor or nurse checks the breasts and underarms for lumps, thickening, or other changes.

2. Imaging tests

Mammogram: Special X-ray to look for suspicious areas.

Ultrasound: Uses sound waves to evaluate lumps or dense breast tissue.

MRI: Sometimes used for people at higher risk or to get more detail.

3. Biopsy (the only way to confirm cancer)

A small sample of breast tissue or cells is taken and examined under a microscope. Types include:

• Core needle biopsy (most common).
• Fine needle aspiration.
• Surgical biopsy (if other methods are unclear).

What the results show

Pathology tests check:

• Type of cancer (e.g., ductal, lobular).
• Hormone receptor status (estrogen/progesterone).
• HER2 status (a protein that may drive cancer growth).
• Grade (how abnormal the cells look).

These details help determine treatment options.

Staging breast cancer

If cancer is found, doctors may order additional tests (such as CT, PET, or bone scans) to see if it has spread. Staging describes how advanced the cancer is and guides therapy.

• Stage 0: Non-invasive (in situ).
• Stage I–III: Early to locally advanced.
• Stage IV: Cancer has spread (metastatic).