PATH 1: Early Stage Breast Cancer

PATH 2: Neoadjuvant Therapy

PATH 3: Pregnancy During Breast Cancer


PATH 5: Metastatic Stage 4

Systemic Therapy

(Post-surgery chemotherapy, endocrine or targeted therapy)

After surgery, you may be given some form of systemic therapy (injections into your veins or oral pills) to kill any remaining cancerous cells and stop them from spreading.

Systemic therapy may include chemotherapy, endocrine therapy or targeted therapy, although the treatment you receive will depend on your cancer type. 

The goal of this step in your treatment is to prevent the breast cancer returning (recurrence) and to kill any remaining cancer cells and stop them from spreading into other parts of the body (metastases). Information about the treatment types--including who is eligible to receive them--along with additional links to prepare yourself can be found on this page.


Systemic therapy is a broad term used for a variety of treatments that involve drugs that will affect the entire body. These include chemotherapy (with various different drugs), endocrine therapy (that affect estrogen levels) and targeted therapy (that are focused on Her-2 positive tumours).

For most women, the decision about treatment with systemic therapy will depend on a number of factors. The choice of systemic therapy should take into account the benefits of the treatment compared to the risks. In determining risk, the main factor for your oncologist to consider will be the likelihood of the cancer recurring in the future. One tool that they may use is an online prediction calculator called Adjuvant Online!. This takes into account many (but not all) of the factors that we will talk about below, including age, other medical conditions, tumour size, grade, lymph node involvement and hormone receptor status. 

The Lymph Nodes

A number of specific indicators based on you and the tumour itself are used to make this assessment. One of the most important factors considered is whether the tumour has spread outside of the breast to involve any of the lymph nodes in the area. These are typically the lymph nodes that are under the arm (axilla) and can either be felt if they are enlarged (clinically palpable), or seen on some imaging tests (such as ultrasound and MRI). 
If the lymph nodes are involved (node-positive), many patients would be recommended to have various forms of systemic therapy. This would include chemotherapy, endocrine therapy (if applicable) and targeted therapy (if applicable).
If the lymph nodes are not involved (node-negative), additional information and future risk may be assessed by looking at features such as a patient’s age, tumour size, grade, hormone receptor status, Her-2 status and presence of tumour in the lymph channels and/or blood vessels (called lymphovascular invasion = LVI).
Therefore, for node-negative patients, those who are deemed to be high risk would often have chemotherapy + endocrine therapy (if applicable) + targeted agent (if applicable). High risk includes age <35, size >2cm, grade 3, estrogen negative and Her-2 positive tumours, and presence of LVI. 
Patients who are node-negative and low risk would have no systemic treatment or endocrine therapy alone. Low risk includes patients includes age >35, size <2cm, grade 1, estrogen positive, Her-2 negative and LVI absent. 
Those in the moderate risk category fall between these two groups. These patients would have endocrine therapy and possibly chemotherapy. They may also be considered to have a specific test on the tumour called Oncotype DX.


There are a few different regimens that are used for treatment with chemotherapy. Most high-risk patients will receive a 3rd generation regimen which includes drugs like FEC and Docetaxel or dose-dense AC and Paclitaxel. They do have added toxicity compared to 1st and 2nd generation regimens. Your oncologist will go over what the best regimen for you may be and the specific risks and benefits of those drugs. 
Some common side effects of chemotherapy include pain, nausea and vomiting, fatigue, hair loss, mouth ulcers, a drop in your blood counts and nervous system effects such as numbness, weakness, tingling or burning. A detailed outline can be found here. There are many remedies that can address these side effects and your oncology team will review them with you.

Endocrine therapy

This category of treatment includes drugs such as Tamoxifen as well as a group of drugs called aromatase inhibitors. These medications can lower the estrogen in your body; therefore, they are only useful for patients that have tumours that respond to estrogen. It results in a reduced risk of the cancer coming back in the breast and in other areas of the body, as well as the risk of developing a new cancer in the non-affected breast. They would usually be started after you’ve completed your surgery, chemotherapy and radiation treatments, and are given for several years.
Tamoxifen is in a category called selective estrogen receptor modulator (SERMs); it may be used for five to ten years. The main side effects are menopausal symptoms such as hot flashes and thinning of the vaginal wall; rarely it can cause a blood clot in the legs or cancer in the uterus. You should not become pregnant while taking Tamoxifen. You can learn more about SERMs here
Aromatase inhibitors are another category of drugs that are useful only for patients that have gone through menopause. There are a few of these specific drugs that can be useful for you, especially after treatment with Tamoxifen for a period of time. They can cause similar side effects but may also result in bone pain and/or have some effects on your heart health. Additional information about aromatase inhibitors can be found here
For some young women (younger than 35 years of age) that have high-risk breast cancer but are still getting periods after their chemotherapy, they may be recommended to have some form of ovarian suppression and take an aromatase inhibitor rather than Tamoxifen

Targeted therapy

Some breast cancer cells have specific receptors on them called Her-2 receptors. These cells tend to be more aggressive and can grow quickly. A specific targeted drug called Herceptin or Trastusumab works to attach itself to the Her-2 receptors on breast cancer cells and stop them from growing.

Patients with Her2-positive breast cancers will be recommended to have Herceptin as part of their systemic therapy. Treatment with Herceptin will last for one year. It may be started with chemotherapy but will be taken longer than the chemotherapy. 

Although it is generally well tolerated, it must be injected every three weeks, so your doctors may recommend a port-a-cath (see neoadjuvant chemotherapy) be inserted to make this easier. 

Some of the side effects of Herceptin include flu-like symptoms. In some cases, it can affect your heart, so this should be monitored as well. 


After you have your surgery, you will meet with your medical oncologist; he or she will review your risk factors and may recommend other tests (e.g. Oncotype) in order to guide the decisions regarding systemic therapy. 
You may need to have other tests to check other areas of the body (see Staging) or to check the function of your heart (and ultrasound or MUGA scan). Your oncologist will order some blood work as well to check your liver function, kidneys and blood counts. 
The best thing to do now is to prepare your body for the next step of treatment. Now that you’ve recovered from surgery, chemotherapy may be the next step. For some patients, working through chemo is an option, but many people will slow down and not work during this period. 


Many patients are very worried about what systemic therapy means in terms of the side effects, both short term and long term. For young women, fertility may be a concern. Be sure to share these concerns with your doctor prior to treatment and ask for a referral to a fertilty specialist who can discuss options, such as embryo freezing or ovarian suppression, that are available to you. This decision aid will help you find more information.

Many women have heard stories from friends and loved ones about common and rare things associated with long and shot term side affects of systemic therapy. Remember you are not alone! There are several support systems in place both locally through your hospital as well as online to help you though this time in your journey. 


During chemotherapy, you will be seeing your medical oncologist and nurse frequently. Afterwards, on long-term endocrine therapy, your medical oncology and family physician will monitor you to see how you are tolerating the drugs and to switch (if applicable) from Tamoxifen to an aromatase inhibitor when it is the right time.