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Stage IA & IB Treatment Options

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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


Hormonal therapy

Targeted therapy


  • 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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