Breast Cancer: Systemic Therapy

Pictured: Diana Lake Medical oncologist Diana Lake is involved in clinical trials to develop better hormonal therapies and other medical approaches to treatment before surgery for breast cancer.

Systemic therapies are drugs that spread throughout the body to eliminate cancer cells. They include include chemotherapy, hormonal therapies, biologic agents, and vaccines.

Memorial Sloan Kettering is a leading center for the development of innovative systemic therapies for breast cancer. Most of the effective systemic therapies for breast cancer that were developed in the past decade have been studied and explored by members of our medical oncology team.

Our physicians pioneered the use of dose-dense chemotherapy for patients with early-stage breast cancer, and led a national clinical trial that proved its benefits. With dose-dense chemotherapy, standard doses of anticancer drugs are given more frequently over time — an approach that has been shown to be effective against breast cancer while minimizing side effects (such as toxicity to the heart). We are also studying different treatment schedules for individual drugs and combinations of drugs to determine how best to provide patients with treatment that is more tolerable and effective for eradicating tumors.

Our physicians were instrumental in developing the drug paclitaxel (Taxol®). We conducted laboratory and clinical studies of therapies that use monoclonal antibodies such as trastuzumab (Herceptin-) and targeted molecular therapies such as lapatinib (Tykerb®), and translated these studies into clinically useful therapies for patients with both early and advanced disease. We are now studying a number of related drugs that kill cancer cells by disrupting their internal signaling pathways and are assessing their use in combination with one other and with conventional drugs used to treat breast cancer.

Our investigators have also developed ways to reduce immune system suppression, which often accompanies chemotherapy, by limiting the dose of drugs that patients can receive. Immunological therapies (including breast cancer vaccines, which are designed to stimulate an immune response against cancer cells) are being developed and studied at our institution.

When Systemic Therapy Is Used

After surgery, some patients need adjuvant systemic therapy. The goal of this treatment is to reduce the risk of breast cancer recurring (coming back) or spreading (metastasizing). Sometimes the treatment is given before the surgery (an approach called neoadjuvant therapy) to help shrink the tumor and make it easier to remove surgically.

Pictured: Clifford Hudis

Memorial Sloan Kettering experts discuss efforts to kill cancer cells by changing the tumor environment and enhancing the immune system.


Whether a woman needs adjuvant therapy and which type best suits her condition depend on a number of factors. These include the presence or absence of cancer cells in her lymph nodes, the size of the tumor, her menopausal status, whether her tumor contains hormone receptors or overproduces certain proteins such as HER2/neu, and whether she has a high recurrence score on OncotypeDx® testing. Clinical trials of new treatments for breast cancer are also available.

Patients with metastatic breast cancer may receive various systemic therapies — chemotherapy, hormonal therapy, targeted agents, or combinations of these — to control the disease. The choice of treatments depends on certain characteristics of the tumor such as hormone receptors, HER2/neu status, and the location of the disease. Patients with metastatic breast cancer may also be eligible to participate in clinical trials of new therapies.

Side Effects of Systemic Therapy

In addition to cancer cells, normal cells are sometimes affected by systemic therapy because these drugs cannot distinguish one from the other. This can result in undesired side effects. However, everyone responds differently to therapy. Some patients experience side effects, while others have none. The absence of side effects does not mean your treatment is not working.

At Memorial Sloan Kettering, your healthcare team has extensive experience administering systemic therapy, and will help you to anticipate and manage the side effects of your treatment.

Learn more about the different types of systemic therapy.