Trastuzumab, more commonly known by its brand name, Herceptin, is a biologic (or targeted) therapy for breast cancer. By inhibiting human epidermal growth factor receptor 2 (Her-2/neu) actions on cancer cells, Herceptin can stop the growth and spread of breast cancer. Taken intravenously, Herceptin is most often used in tandem with chemotherapy or hormone therapy. It is known as a targeted therapy because it kills only the cancer cells impacted by the Her-2/neu protein and does not damage any other cells.
The Herceptin regimen usually calls for an initial 90-minute dose with follow-up dosages of shorter duration a week to three weeks later. Studies have yet to prove the most effective duration. Herceptin can cause negative side effects for some patients; the U.S. Food and Drug Administration (FDA) requires that patients be screened for proper heart function before starting (and during) Herceptin treatment. Before you begin treatment, your medical team should go over side effects that may occur and offer suggestions to combat or mitigate them.
Like Herceptin, Tykerb targets the HER2 protein. It is approved for the treatment of advanced metastatic breast cancer, but it typically reserved for women who have already tried Herceptin without positive results.
Side effects of Tykerb include vomiting, diarrhea, nausea, fatigue, rash, mouth sores, and pain in the hands and feet known as neuropathy.
Avastin is a drug therapy that starves cancer cells by preventing the tumor cells from communicating with nearby blood vessels and may prevent the tumor from connecting to the blood supply. Without a blood supply bringing fresh oxygen and nutrients to the tumor, the cancer cells die.
Side effects of bevacizumab include fatigue, high blood pressure, blood clots, headaches, heat damage, and mouth sores.
The Food and Drug Administration approved bevacizumab in 2004. In 2008, it was approved for use in metastatic breast cancer amidst controversy because the advisoryl panel advised against approval because while the drug may help slow the growth of cancer cells, research hasn’t been able to show the drug can increase a person’s survival rate. In 2010, the drug was revoked for the use of advanced breast cancer, but doctor’s can still prescribe it for “off-label use,” although insurance companies are less likely to cover it.
There are dozens of chemotherapy drugs approved by the FDA for the treatment of breast cancer. Certain chemotherapy drugs for breast cancer are used more commonly than others. Among these:
- Cyclophosphamide (Cytoxan) blocks the copying of DNA in cancer cells, thus inhibiting their growth.
- Docetaxel (Taxotere) interferes with cell division, slowing the disease’s development.
- Doxorubicin (Adriamycin) is an anthracycline drug, which is derived from strep bacteria and is one of the more effective broad spectrum chemotherapy agents.
- Fluorouracil (Adrucil) blocks enzymes required for DNA production by cancer cells.
- Methotrexate (Trexall) blocks an enzyme needed by cancer cells to live.
- Paclitaxel (Taxol), a taxane like docetaxel, disrupts cell division.
Chemotherapy protocols (the professionally approved drug delivery plans) often combine the agents above and others in dosages, including two or more drugs to enhance their power and to decrease the chance that the cancer will return. Accordingly, the expectation is that combination therapy will allow women with breast cancer to live longer.
One combination that is gaining favor among clinicians is aimed at women whose estrogen receptor-negative breast cancer has spread to the lymph nodes. For them, many oncologists prescribe an anthracycline such as cyclophosphamide followed by a taxane (docetaxel or paclitaxel). This combo has been shown to reduce the chance of a relapse and to confer a longer life for the women who take it.
A similarly population-specific treatment is for women with Her-2/neu cancer. For them, a course of chemotherapy used together with Herceptin (trastuzumab) significantly decreases the risk of recurrence and even, regardless of whether it is a recurrence, bolsters chances for increased longevity.
Side effects may occur with any chemotherapy drug. Depending on slight differences in regimens, in the drugs themselves, and in the individuals involved, some may experience side effects and others not from the same chemo protocol. Common side effects include hair loss, digestive tract complications, mouth sores, and low blood counts, which can cause fatigue, easier bruising, or infection. Before you begin any chemotherapy, your medical team should go over side effects that may occur and suggestions to combat or mitigate them.
This synthetic hormone decreases the risk of recurrence in women with either early-stage or metastatic (spreading) hormone receptor-positive breast cancer. Tamoxifen blocks the expression of estrogen, which reduces the chances for recurrence or new tumor development. It is appropriate for both pre- and postmenopausal women who are hormone receptor-positive. Tamoxifen won’t work for breast cancers that are not estrogen-sensitive, nor does it work for women who do not have an enzyme, CYP2D6, which activates the drug.
Tamoxifen is usually given daily for five years, which thus far appears to be the optimal length of treatment. Side effects from it are usually irregular periods, vaginal discharges, and hot flashes. There is also a low risk for leg or lung blood clots and different kinds of uterine cancer.
Postmenopausal hormone receptor-positive women are the prime candidates for aromatase inhibitor (AI) therapy. AI drugs include:
- Anastrozole (Arimidex)
- Exemestane (Aromasin)
- Letrozole (Femara)
All three work by prompting a significant drop in your body's estrogen levels. (Aromatase is an enzyme that allows the conversion of androstenedione to estrogen; stopping the enzyme greatly lowers the output of estrogen.)
Aromatase inhibitors can work as well as tamoxifen and are often used in conjunction with tamoxifen; AI drugs can be used alone if a woman cannot take tamoxifen. Many cancer specialists recommend that adjuvant therapy for hormone receptor-positive breast cancer in postmenopausal women include an aromatase inhibitor—either initially or after a course of tamoxifen—to reduce the chances for recurrence.
Possible long-term effects of the lowered estrogen caused by both tamoxifen and AI therapy could put you at greater risk of osteoporosis. Accordingly, your doctor may monitor your bone mineral density while you're taking the medication. Lower estrogen levels also may lead to vaginal dryness and irritation