Treatments for stage 1 breast cancer

The following are treatment options for stage 1 ductal carcinoma and lobular carcinoma. Stage 1 is divided into stage 1A and stage 1B, which doctors consider early stage breast cancer. Your healthcare team will suggest treatments based on your needs and work with you to develop a treatment plan.


Surgery is the main treatment for stage 1 breast cancer.

Breast-conserving surgery is offered if doctors can remove all of the tumour along with a margin of healthy tissue around it and there will still be enough tissue for the breast to look as natural as possible after surgery.

Mastectomy is offered if there is cancer in more than one area of the breast or in the tissue removed along with the tumour during breast-conserving surgery (called positive surgical margins). It is also offered if a tumour isn’t found in the breast but a very small amount of cancer is in the lymph nodes (stage 1B). A woman may also choose to have a mastectomy.

Sentinel lymph node biopsy (SLNB) is often offered for early stage breast cancer. If the results of the SLNB show that there is cancer in the sentinel lymph node, or if the sentinel node can’t be found, a woman may be offered a choice between radiation therapy or an axillary lymph node dissection (ALND).

Radiation therapy

External beam radiation therapy is offered after breast-conserving surgery for stage 1 breast cancer. All of the breast and the lymph nodes under the arm and near the collarbone are treated. An extra dose, or boost, of radiation may be given to the area where the tumour was removed.

Radiation therapy is not usually offered after mastectomy for stage 1 breast cancer. It may be given if there was a positive sentinel node found during SLND.

When chemotherapy is a part of the treatment plan, radiation therapy will be given after chemotherapy is finished.

Hormonal therapy

Hormonal therapy is often offered for hormone receptor–positive stage 1 breast cancer.

Tamoxifen (Nolvadex, Tamofen) is the most commonly used anti-estrogen hormonal therapy drug offered to both premenopausal and post-menopausal women.

Aromatase inhibitors are given only to post-menopausal women. They may be offered after tamoxifen therapy or instead of tamoxifen if you can’t take or would prefer not to take tamoxifen. The most common aromatase inhibitors used are:

  • letrozole (Femara)
  • anastrozole (Arimidex)
  • exemestane (Aromasin)

Hormonal therapy for post-menopausal women

Hormonal therapy for post-menopausal women with stage 1 breast cancer includes tamoxifen (an anti-estrogen) and aromatase inhibitors.

You may be offered one of the following options:

  • tamoxifen (Nolvadex, Tamofen) alone for up to 10 years
  • an aromatase inhibitor alone for up to 10 years
  • tamoxifen for 5 years, and then an aromatase inhibitor for up to 5 years (for up to a total of 10 years of hormonal therapy)
  • tamoxifen for 2 to 3 years followed by an aromatase inhibitor for 2 to 3 years, or starting with an aromatase inhibitor followed by tamoxifen, for a total of 5 years of hormonal therapy
  • an aromatase inhibitor for 2 to 3 years, followed by tamoxifen

Hormonal therapy for premenopausal women

Hormonal therapy options for premenopausal women with stage 1 breast cancer include the following.

You will take tamoxifen for 5 years, then your healthcare team will check if you have reached menopause:

  • If you are still premenopausal, you can continue to take tamoxifen for up to 10 years in total.
  • If you have reached menopause, your healthcare team may offer you the option to continue tamoxifen for up to 10 years in total or to switch to an aromatase inhibitor for up to 5 years (for up to a total of 10 years of hormonal therapy).

Older premenopausal women may be offered ovarian ablation or suppression, along with tamoxifen or an aromatase inhibitor, for up to 10 years.


Chemotherapy is not usually offered for stage 1 breast tumours. It may be offered after surgery (called adjuvant therapy) for these tumours if there is a high risk that the cancer will come back (recur). Find out more about the risk of breast cancer recurrence and adjuvant therapy.

The most common combinations of chemotherapy drugs offered for stage 1 breast cancer that has a high risk of recurrence are:

  • AC-T – doxorubicin (Adriamycin) and cyclophosphamide (Procytox) followed by paclitaxel (Taxol) or docetaxel (Taxotere)
  • T-AC – paclitaxel or docetaxel followed by doxorubicin and cyclophosphamide
  • TC – paclitaxel and cyclophosphamide
  • CAF (or FAC) – cyclophosphamide, doxorubicin and 5-fluorouracil (Adrucil, 5-FU)
  • CAF followed by docetaxel or paclitaxel
  • CEF (or FEC) – cyclophosphamide, epirubicin (Pharmorubicin) and 5-fluorouracil
  • CEF followed by docetaxel or paclitaxel
  • EC – epirubicin and cyclophosphamide

Targeted therapy

Trastuzumab (Herceptin) is added to chemotherapy for stage 1 breast cancer that is HER2-positive and has a high risk for recurrence. It is usually given for up to a year after chemotherapy for breast cancer has finished.

Pertuzumab (Perjeta) may be used in combination with trastuzumab and chemotherapy:

  • as the main treatment for stage 1A and 1B HER2-positive breast cancer

  • for hormone receptor–negative breast cancer

  • before surgery for stage 1A and 1B HER2-positive breast cancer

Phesgo combines pertuzumab and trastuzumab into a single dose. It is given by a needle just under the skin (subcutaneously) instead of through a needle in a vein (intravenously). This means that treatment can be given more quickly and easily than giving the 2 drugs separately. Phesgo may be used in combination with chemotherapy for stage 1 HER2-positive breast cancer that has not spread to more than 3 lymph nodes and for hormone receptor–negative breast cancer.

Neratinib (Nerlynx) may be used to treat women with early-stage hormone receptor-positive and HER2-positive breast cancer after they have completed a year of trastuzumab therapy.

Trastuzumab emtansine (Kadcyla, T-DM1) may be used to treat HER2-positive breast cancer if there is still evidence of cancer after being treated with chemotherapy and trastuzumab.

Clinical trials

Many clinical trials in Canada are open to women with breast cancer. Clinical trials look at new ways to prevent, find and treat cancer. Find out more about clinical trials.

Expert review and references

  • Hoffman La Roche Canada. Product Monograph: Phesgo.
  • Roche Canada. Product Monograph Trastuzumab Emtansine (Kadcyla).
  • American Cancer Society. Breast Cancer. 2015:
  • Brackstone M, Fletcher GG, Dayes IS, Madarnas Y, SenGupta SK, Verma S, and Members of the Breast Cancer Disease Site Group . Locoregional therapy of locally advanced breast cancer: a clinical practice guideline. Current Oncology. 2015.
  • Burstein HJ, Temin S, Anderson H, Buchholz TA, Davidson NE, Gelmon KE, Giordano SH, et al . Adjuvant endocrine therapy for women with hormone receptor-positive breast cancer: American Society of Clinical Oncology clinical practice guideline focused update. Journal of Clinical Oncology. 2014.
  • Eisen A, Fletcher GG, Gandhi S, Mates M, Freedman OC, Dent SF, Trudeau ME and members of the Early Breast Cancer Systemic Therapy Consensus Panel . Optimal systemic therapy for early breast cancer in women: a clinical practice guideline. Current Oncology. 2015.
  • Goss, PE, Ingle JN, Pritchard KJ, et al . Extending aromatase-inhibitor adjuvant therapy to 10 years. New England Journal of Medicine. 2016.
  • Hoffmann-La Roche Limited. Product Monograph: Perjeta. 2018.
  • Morrow M, Burstein HJ, and Harris JR . Malignant tumors of the breast. DeVita VT Jr, Lawrence TS, & Rosenberg SA. Cancer: Principles and Practice of Oncology. 10th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2015: 79: 1117-1156.
  • National Cancer Institute. Breast Cancer Treatment for Health Professionals (PDQ®). 2015.
  • National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Breast Cancer (Version 2.2015).

Medical disclaimer

The information that the Canadian Cancer Society provides does not replace your relationship with your doctor. The information is for your general use, so be sure to talk to a qualified healthcare professional before making medical decisions or if you have questions about your health.

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The Canadian Cancer Society is not responsible for the quality of the information or services provided by other organizations and mentioned on, nor do we endorse any service, product, treatment or therapy.

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