Chemoprevention and hormonal therapies involve the use of systemic agents to lower the risk of developing cancer. Chemotherapy or hormonal therapies may be used as sole treatments, or they may be used in conjunction with other therapies for other patients. Adjuvant therapy is the use of these drugs after surgery to prevent the growth of cancer cells that may remain in the breast. Studies have shown that by eradicating cancer cells that remain in the breast after surgery or radiation, the use of adjuvant chemotherapy or adjuvant hormonal therapy significantly increases women's chances of long-term survival.
The increase in breast cancer survival is largely due to the benefits of hormonal therapy, such as tamoxifen and aromatase inhibitors (AIs), for the treatment of hormone-sensitive breast cancer. These systemic agents work to either block estrogen from stimulating the cancer cell (tamoxifen), or by reducing the amount of estrogen produced in the body (AIs).
Recent clinical trials have demonstrated that AIs are more effective than tamoxifen at reducing breast cancer recurrences in post-menopausal women, but for pre-menopausal women, tamoxifen is the treatment of choice. Many patients treated at Columbia University Medical Center have participated in national clinical trials to study these treatments and to better understand the optimal duration of their use.
Tamoxifen is approved for use in prevention, but it is not commonly used for this purpose because of its side effects (including hot flashes, increased risk of uterine cancer, and blood clots). A similar drug, raloxifene, approved for treatment of osteoporosis, has fewer side effects than tamoxifen; this drug is currently pending FDA approval as an agent to reduce risk of breast cancer.
Learn more about chemotherapy and hormonal therapies here.
The Clinical Breast Cancer Program is conducting studies of several agents that may help to reduce the risk of breast cancer. Current studies include oral green tea extract, vitamin D, and others.
Oral Green Tea Extract
Epidemiologic and animal studies show that an antioxidant found in green tea may have antitumor effects. Columbia is the lead center in a study funded by the National Cancer Institute to 1) determine the safety and appropriate dosage of the compound, and 2) examine the biologic effects of green tea in breast tissue. Eligible women include those who have already been treated for hormone receptor-negative breast cancer and who are at high risk of developing cancer in the opposite breast.
The researchers will begin the study by conducting mammograms on each participant. After patients take oral green tea extract for six months, they will have a second mammogram. The researchers will look at changes in cell structure to see whether density of the breast tissue has been reduced, because lowering the breast density may reduce the risk of breast cancer.
A capsule form provides a pharmacologic dose of the antioxidant compound but without the caffeine that would be present in the equivalent dosage in liquid form—which would require drinking more than ten cups of tea per day.
Vitamin D Study
Hormone receptor negative breast cancer does not respond to tamoxifen and is associated with a poorer prognosis than hormone receptor positive breast cancer. Pharmacologic agents prescribed to reduce the risk this type of cancer, must work by non-hormonal mechanisms.
A pilot study at Columbia will be the first to assess the feasibility of studying high dose vitamin D as an agent for chemoprevention. This is based on evidence from a recent Women's Health Initiative that suggested calcium and vitamin D were beneficial in reducing breast cancer incidence in a supgroup of healthy postmenopausal women. After an initial safety study, a larger multicenter study is expected to follow.