Stage I describes invasive breast cancer (cancer cells are breaking through to or invading normal surrounding breast tissue). Stage I is divided into subcategories known as IA and IB.
In general, stage IA describes invasive breast cancer in which:
- the tumor measures up to 2 centimeters (cm) and
- the cancer has not spread outside the breast; no lymph nodes are involved
In general, stage IB describes invasive breast cancer in which:
- there is no tumor in the breast; instead, small groups of cancer cells — larger than 0.2 millimeter (mm) but not larger than 2 mm — are found in the lymph nodes or
- there is a tumor in the breast that is no larger than 2 cm, and there are small groups of cancer cells — larger than 0.2 mm but not larger than 2 mm — in the lymph nodes
Still, if the cancer is estrogen-receptor-positive or progesterone-receptor-positive, it is likely to be classified as stage IA.
Treatment to the breast
- total mastectomy; radiation after mastectomy is only rarely needed or
- lumpectomy plus radiation or
- very occasionally, lumpectomy alone, with or without internal radiation — only for a limited subset of women
Treatment to the lymph nodes
- sentinel lymph node biopsy, also known as sentinel lymph node dissection (preferred approach) or
- axillary lymph node biopsy
- chemotherapy may be given to reduce the risk of recurrence
- hormonal therapy is prescribed for people with hormone-receptor-positive cancer
- targeted therapy medicines may be used to treat cancers that have certain characteristics (for example, cancers that are HER2-positive)
- immunotherapy may be recommended before and after surgery if the cancer is triple-negative
Treatment to other parts of the body
- does not apply
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