Breast cancer

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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 for stage 1 HER2-positive breast cancer in women with lymph node positive or hormone receptor-negative disease.

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.

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.


The time before menopause.

Premenopausal means referring to or having to do with the time before menopause.


The time after menopause.

Post-menopausal means referring to or having to do with the time after menopause.

aromatase inhibitor

A drug that stops the production or blocks the actions of the enzyme aromatase, which in turn lowers the level of estradiol (a female hormone) in the body.

Aromatase inhibitors are a type of anti-estrogen therapy.