Treatments for stage 0 breast cancer

The following are treatment options for stage 0 (non-invasive, or in situ) breast cancer. Your healthcare team will suggest treatments based on your needs and work with you to develop a treatment plan.

Ductal carcinoma in situ (DCIS) is the most common type of non-invasive breast cancer. Lobular carcinoma in situ (LCIS) increases a woman’s risk for developing breast cancer, but it is not considered a cancer.


Surgery is the main treatment for DCIS. Most women are offered breast-conserving surgery. If there are several areas of DCIS in the breast, doctors may do a mastectomy to make sure that all of the cancer is removed. Doctors do not remove lymph nodes under the arm (called axillary lymph node dissection) for DCIS because this cancer has not spread outside the duct in the breast.

To lower their risk of developing invasive breast cancer, some women with LCIS may choose to have their breasts removed (called a prophylactic mastectomy).

Radiation therapy

External beam radiation therapy is usually given after breast-conserving surgery for DCIS. It is used to lower the risk that cancer will come back (recur) in the breast, especially if there is high-grade DCIS. In rare cases, radiation therapy isn’t needed because the DCIS is low grade, it is only in one very small area of the breast and it is completely removed with surgery.

LCIS is not treated with radiation therapy.

Hormonal therapy

Hormonal therapy may be offered after breast-conserving surgery for hormone receptor–positive DCIS. It can lower the risk of DCIS or invasive cancer in that breast and the other breast.

Hormonal therapy may be offered after a mastectomy to lower the risk of cancer in the other breast.

The most common type of hormonal therapy used is tamoxifen (Nolvadex, Tamofen). An aromatase inhibitor may be used for post-menopausal women.

Women with LCIS may be offered hormonal therapy to lower the risk that an invasive breast cancer will develop.

Find out more about hormonal therapy for breast cancer.

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

  • American Cancer Society. Breast Cancer. 2015:
  • 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.

We do our best to make sure that the information we provide is accurate and reliable but cannot guarantee that it is error-free or complete.

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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