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Breast cancer

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Treatment of stage I breast cancer

The following are treatment options for stage I breast cancer. The types of treatments given are based on the unique needs of the woman with cancer.

Invasive ductal and invasive lobular carcinomas are treated the same way.


Surgery is the primary treatment for stage I breast cancer. The types of surgery are:

  • breast-conserving surgery (BCS)
  • modified radical mastectomy
  • lymph node procedures
    • sentinel lymph node biopsy
    • axillary lymph node dissection

The risk of breast cancer recurrence will influence the type of adjuvant therapy offered after surgery for stage I breast cancer. These treatments may be used alone or in combination to reduce the chance of breast cancer recurrence and improve survival. Adjuvant therapy is often started 4–12 weeks after breast cancer surgery.

Radiation therapy

External beam radiation therapy is almost always offered after BCS for stage I breast cancer. It may also be offered after a mastectomy if the tumour has invaded the skin or muscles of the chest wall.

Hormonal therapy

Hormonal therapy may be offered to women who have stage I breast cancer that is hormone receptor positive (ER+, PR+ or both).

The types of hormonal therapy offered for stage I breast cancer are:

  • anti-estrogens
    • tamoxifen (Nolvadex, Tamofen) – the most common anti-estrogen
      • Tamoxifen is used to treat both premenopausal and post-menopausal women.
      • Post-menopausal women may be switched to an aromatase inhibitor after a period of time on tamoxifen.
  • aromatase inhibitors – used only in post-menopausal women
    • letrozole (Femara)
    • anastrozole (Arimidex)
    • exemestane (Aromasin)
  • ovarian ablation – may be offered to premenopausal women who do not wish to take other types of hormonal therapy


Chemotherapy may be offered for stage I breast cancer:

  • that has a high risk of recurrence
    • Women with an intermediate risk of recurrence may also be offered chemotherapy.
    • Women with a low risk of breast cancer recurrence are not usually offered chemotherapy.
  • that is hormone receptor negative
  • in women with hormone receptor–positive tumours who do not wish to have hormone therapy

Chemotherapy for breast cancer is not usually given as a single drug. Drugs are more commonly used in combination with one another because this has been shown to be more effective.

The most common chemotherapy combinations used to treat stage I breast cancer are:

  • AC
    • doxorubicin (Adriamycin) and cyclophosphamide (Cytoxan, Procytox)
  • AC – Taxol
    • doxorubicin and cyclophosphamide, followed by paclitaxel (Taxol)
  • AC – Taxol (Dose Dense)
    • doxorubicin and cyclophosphamide, followed by paclitaxel, with less time between treatments (dose dense)
      • This combination is usually given with filgrastim (Neupogen) or pegfilgrastim (Neulasta).
  • TC
    • docetaxel (Taxotere) and cyclophosphamide
  • TAC (or DAC)
    • docetaxel, doxorubicin and cyclophosphamide
  • FAC (or CAF)
    • cyclophosphamide (by mouth), doxorubicin and 5-fluorouracil (Adrucil, 5-FU)
  • CEF
    • cyclophosphamide (by mouth), epirubicin (Pharmorubicin) and 5-fluorouracil
  • FEC
    • cyclophosphamide (into a vein – intravenous), epirubicin and 5-fluorouracil
  • FEC – T
    • cyclophosphamide, epirubicin and 5-fluorouracil, followed by docetaxel
  • CMF – IV
    • cyclophosphamide (intravenous), methotrexate and 5-fluorouracil
  • CMF – PO
    • cyclophosphamide (by mouth), methotrexate and 5-fluorouracil
  • Taxol – FAC
    • paclitaxel, followed by cyclophosphamide, doxorubicin and 5-fluorouracil

For more detailed information on specific drugs, go to sources of drug information.

Biological therapy

Women with HER2-positive stage I breast cancer may also be offered trastuzumab (Herceptin) with certain chemotherapy combinations.

Clinical trials

Women with stage I breast cancer may be offered the opportunity to participate in clinical trials. For more information, go to clinical trials.


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