 |
A recent study found that a drug called ibandronate successfully reduced the number of
breast cancer cells in the bones of mice. Ibandronate belongs to a class of drugs called
bisphosphonates that scientists have been studying to determine whether they can block the
progression of breast cancer cells that have spread to the bone. One bisphosphonate, Aredia (genetic name, pamidronate disodium), has already
been approved by the U.S. Food and Drug Administration (FDA) to help treat bone metastases
caused by breast cancer while a number of other bisphosphonates are currently under
investigation for this use. With these advances in research, the American Society of
Clinical Oncology (ASCO) recently published guidelines on the role of bisphosphonates in
breast cancer.
When breast cancer spreads past the breast and axillary (armpit) lymph nodes, it often spreads first to the bone. These
breast cancer tumors in the bone are called "bone metastases." As advanced
breast cancer dissolves portions of bone, a variety of problems can occur. Bone metastases
can cause pain, decreased activity, and potentially severe problems such as fractures.
Other complications that can arise from bone metastases include the surgical treatment for
fractures, hypercalcemia (abnormally high levels of calcium), and spinal cord compression
(vertebral damage due to pressure on the spinal cord).
According to an expert panel of the American Society of Clinical Oncology (ASCO),
bisphosphonates have shown benefits in reducing bone complications. However,
bisphosphonates have not had an impact on patient survival (i.e., patients do not live
longer if they take bisphosphonates). Thus, bisphosphonates are used to improve a
patient’s quality of life rather than cure the disease. While bisphosphonates can be
helpful, the ASCO believes they should not replace current standards of treatment for
cancer pain, such as local radiation therapy and other
medications.
In addition to treating bone metastases, bisphosphonates are also being studied to see
if they can play a role in the prevention of metastatic breast
cancer (breast cancer that has spread to other organs, such as the bone, liver, lung,
etc.). Some bisphosphonates, such as Fosamax (generic name,
alendronate), are already used to treat osteoporosis,
a degenerative bone disease primarily affecting post-menopausal women.
Currently, Aredia is the only FDA-approved bisphosphonate to treat breast cancer
patients with bone metastases. Aredia is administered intravenously (through a vein) along
with other cancer treatments, such as chemotherapy. Clinical
studies have shown that breast cancer patients with bone metastases who are given Aredia
tend to experience a delay in or reduction of bone pain, fractures, and other bone
complications compared to patients who do not receive Aredia. Possible side effects of
Aredia include fever, fatigue, nausea and vomiting, initial bone pain, lack of appetite,
and anemia (decrease in red blood cells).
Other bisphosphonates have also shown promise in alleviating symptoms of bone
metastases. In the most recent study on bisphosphonates, ibandronate stopped the
progression of bone metastases in mice and halted the formation of new metastases. Other
bisphosphonates under investigation for treating bone metastases include:
- Didronel (generic name, etidronate)
- Bonefos, Clostoban, Loron, Ostac (generic name, clodronate)
- Skelid (generic name, tiludronate)
- Fosamax (generic name, alendronate)
- Zometa (generic name, zoledronate)
At this time, most physicians do not see sufficient evidence to recommend
bisphosphonates for breast cancer patients who do not already have bone metastases.
Advanced, or metastatic, breast cancer describes a cancer that has spread from the
breast to distant organs in the body. After the axillary lymph nodes, breast cancer most
often spreads first to the bone. The lungs and liver are other common sites that breast
cancer affects. Treatment of metastatic breast cancer generally focuses on relieving
symptoms and extending a woman’s lifetime. The National Cancer Institute estimates
that approximately 10% to 20% of women with metastatic breast cancer survive the disease.
According to the ASCO, the average breast cancer patient whose cancer has spread only to
the bone survives 36 months compared to an average of 18 to 24 months for breast cancer
patients whose cancer has spread to other regions of the body, such as the liver, lung,
brain, etc.
The chances of successful treatment and survival of breast cancer are much greater when
the cancer is detected and treated before it has spread beyond the breast. Therefore, all
women should follow the guidelines for early breast cancer detection:
- All women between 20 and 39 years of age should practice monthly breast
self-exams and have physician performed clinical
breast exams at least every three years.
- All women 40 years of age and older should have annual screening
mammograms, practice monthly breast self-exams, and have yearly clinical breast exams.
The clinical breast exam should be conducted close to and preferably before the scheduled
mammogram.
- Younger women with a family or personal history of breast cancer should talk to their
physicians about beginning annual mammograms before age 40.
Additional Resources and References
Return to Breast Health News Archives |
