Unlike local treatments, which focus on the area (or areas) where the invasive ductal carcinoma (IDC) was found, systemic treatments involve the entire body. Treatments such as chemotherapy, hormonal therapy, and targeted therapies are used to destroy any cancer cells that may have left the original tumor, as well as to reduce the risk of the IDC coming back.
Chemotherapy medicines are often given by IV infusion, which means the medicine is delivered directly into your bloodstream through an IV or a port. Other chemotherapy medicines are taken by mouth in the form of a pill. Two or more chemotherapy medicines are often given in combination. The medicines travel through the bloodstream to all parts of the body. As chemotherapy damages the cancer cells, it also can damage some of the body’s healthy cells, which is why you may experience side effects.
If the IDC is larger than 1 centimeter in diameter and/or has spread to the lymph nodes, chemotherapy is usually recommended or, at the very least, seriously considered. When chemotherapy is given after surgery, it is called adjuvant therapy. In cases where the tumor is large, or breast cancer cells have traveled to many lymph nodes or other parts of the body, chemotherapy may be given before surgery to shrink the cancer. This approach is called neoadjuvant therapy. In either case, chemotherapy will be given in cycles, usually with a day (or days) of treatment followed by a period of “off” days. The exact schedule can vary depending on the medication or medications used. An entire course of chemotherapy usually takes about 3 to 6 months.
Some examples of the many chemotherapy medicines that may be used to treat IDC are:
- Adriamycin (chemical name: doxorubicin)
- Ellence (chemical name: epirubicin)
- Cytoxan (chemical name: cyclophosphamide)
- Taxotere (chemical name: docetaxel)
- Taxol (chemical name: paclitaxel)
- Xeloda (chemical name: capecitabine)
- Ixempra (chemical name: ixabepilone)
- fluorouracil (also called 5-fluorouracil or 5-FU)
You and your doctor will work together to determine which chemotherapy treatments are best for your situation. This can depend on the features of the cancer and any other health conditions you may have. For example, if you have a history of heart disease or heart-related risk factors, you and your doctor will want to avoid medications that can affect the heart. Your decision also will be influenced by whether or not the tumor tested positive for HER2 receptors. Some chemotherapies, such as Taxol and Cytoxan, are more commonly used with Herceptin (chemical name: trastuzumab) in treating HER2-positive breast cancers.
Tests to determine the need for chemotherapy
If the cancer is small, early-stage, has not spread to the lymph nodes, and you will be taking hormonal therapy (see below), you may wonder whether chemotherapy is truly necessary. You and your doctor can discuss whether or not chemotherapy is right for your situation. You also may be eligible for a genomic test, which is used to predict how likely the cancer is to recur (come back). Genomic tests look at certain genes in the cancer tumor to assess the risk of recurrence. Visit the Breast Cancer Tests page for more information about each test.
Doctors do not automatically order genomic testing for every breast cancer. Instead, they typically reserve these tests for people who have early-stage breast cancer that has not spread to the lymph nodes, or to just a few; or have ductal carcinoma in situ (DCIS). If you fit these criteria, you and your doctor can decide if genomic testing is right for you.
If the cancer tested positive for hormone receptors, your doctor likely will recommend some form of hormonal therapy. In some cases of advanced-stage IDC, hormonal therapy can be given before surgery to help shrink the cancer. Still, it's more common for hormonal therapy to start after other treatments, such as chemotherapy or radiation therapy, unless these treatments aren’t needed.
Hormone receptors are special proteins found on the surface of certain cells throughout the body, including breast cells. These receptor proteins are the “eyes” and “ears” of the cells, receiving messages from the hormones in the bloodstream and then telling the cells what to do. In other words, the receptors act like an on-off switch for a particular activity in the cell. If the right substance comes along that fits into the receptor — like a key fitting into a lock — the switch is turned on and a particular activity in the cell begins.
When breast cells have hormone receptors, estrogen and/or progesterone can attach to those receptors and tell the cell to grow and divide. Many breast cancer cells have high numbers of receptors for estrogen, progesterone, or both. This means that when these hormones are present, the cells receive a strong message to keep on growing and dividing — and this creates more cancer. If you take the hormone away or block it, the cancer cells don't receive the instructions to grow and divide and are less likely to survive.
Hormonal therapy, also called anti-estrogen therapy, works by lowering the amount of estrogen in the body or blocking the estrogen from signaling breast cancer cells to grow. You and your doctor will work together to decide which form of hormonal therapy is best in your situation. Two types of hormonal therapy are most frequently used:
- Selective estrogen-receptor response modulators (SERMs): The best-known SERM is tamoxifen. Tamoxifen acts like estrogen and attaches to the receptors on the breast cancer cells, taking the place of real estrogen. As a result, the cells don’t receive the signal to grow. Other examples of SERMs are Evista (chemical name: raloxifene) and Fareston (chemical name: toremifene). Tamoxifen can be used to treat both pre- and postmenopausal women.
Aromatase inhibitors: The aromatase inhibitors are:
- Arimidex (chemical name: anastrozole)
- Aromasin (chemical name: exemestane)
- Femara (chemical name: letrozole)
Aromatase inhibitors reduce the amount of estrogen your body produces. Aromatase inhibitors are most commonly used to treat postmenopausal women, but can be used to treat premenopausal women who are also taking medicine to shut down their ovaries.
Other types of hormonal therapy include:
- Estrogen-receptor downregulators (ERDs): ERDs destroy the estrogen receptors in cells, which prevents the estrogen from getting its message through. Faslodex (chemical name: fulvestrant) is an ERD used to treat postmenopausal women diagnosed with advanced-stage or metastatic breast cancer.
Ovarian shutdown or removal: The ovaries are the main source of estrogen in women before menopause. Shutting the ovaries down temporarily (for a set period of time), or even permanently, can reduce the amount of estrogen in the body. Ovarian shutdown methods include:
- Medicines such as Zoladex (chemical name: goserelin) and Lupron (chemical name: leuprolide), given by injection once a month for several months to stop the ovaries from producing estrogen.
- Surgery to remove the ovaries, called oophorectomy.
If the IDC is HER2-positive, then its cells make too much of a protein called HER2, and they also have too many HER2 receptors on the cell's surface. With too many receptors, breast cancer cells pick up too many growth signals and start growing too much and too fast. One way to slow down or stop the growth of the cancer cells is to block the receptors at the cell surface so they don't pick up as many growth signals. There are a number of medicines used to treat HER2-positive breast cancer. Because these medicines target HER2 receptors or the HER2 protein, they are considered targeted therapies.
- Herceptin (chemical name: trastuzumab) works against HER2-positive breast cancers by blocking the ability of the cancer cells to receive the chemical signals that tell the cells to grow. Herceptin can be used to treat both early-stage and advanced-stage HER2-positive breast cancer. Herceptin is given as an IV infusion, which means the medicine is delivered directly into your bloodstream through an IV or a port. A newer form of Herceptin, Herceptin Hylecta (chemical name: trastuzumab and hyaluronidase-oysk), can be given as an injection. Herceptin may be given as part of a chemotherapy regimen or in combination with Perjeta (chemical name: pertuzumab), another HER2 targeted therapy. Herceptin can cause damage to the heart, so it may not be recommended for people with certain heart conditions or heart-related risk.
- Tykerb (chemical name: lapatinib) works inside the cell to disrupt protein signals that tell the cell to grow and divide abnormally. Tykerb is used to treat advanced-stage HER2-positive breast cancer. Tykerb is a pill taken by mouth.
- Perjeta (chemical name: pertuzumab) works like Herceptin by attaching itself to the HER2 receptors on the surface of breast cancer cells and blocking them from receiving growth signals. Perjeta targets a different area on the HER2 receptor than Herceptin does, so it’s believed to work in a way that’s complementary to Herceptin. Perjeta is used in combination with Herceptin and chemotherapy to treat early-stage and advanced-stage HER2-positive breast cancer. Perjeta is given as an IV infusion, which means the medicine is delivered directly into your bloodstream through an IV or a port.
- Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine) is a combination of Herceptin and the chemotherapy medicine emtansine. Kadcyla was designed to deliver emtansine to cancer cells in a targeted way by attaching emtansine to Herceptin. Herceptin then carries emtansine to HER2-positive cancer cells. Kadcyla is used to treat metastatic HER2-positive breast cancer. Kadcyla is given intravenously, which means it’s delivered directly into your bloodstream through an IV or port.
- Nerlynx (chemical name: neratinib) works by blocking the cancer cells’ HER2 receptors from receiving growth signals. Nerlynx is used to treat early-stage HER2-positive breast cancer for an extended period of time after surgery. Nerlynx is a pill taken by mouth.