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Between 70% and 91% of breast cancer patients undergo additional treatments, such as chemotherapy, after breast cancer surgery, according to an
editorial in the journal, Nature. These supplemental, or "adjuvant,"
therapies are designed to help destroy any remaining cancer cells and prevent the cancer
from returning. However, researchers have found that many breast cancer patients may not
need these adjuvant therapies. According to a new study, a certain pattern of genetic
activity within breast cancer cells can help researchers determine whether a
patient’s cancer is aggressive or non-aggressive.
Though the findings are preliminary, experts predict that the future of cancer
treatments will rely heavily on molecular genetics.
To conduct their study, lead researcher Laura J. van 't Veer, of the Netherlands Cancer
Institute in Amsterdam and her colleagues analyzed 25,000 genes in 78 breast cancer tumor
samples. Of the 78 patients, 34 patients eventually developed metastatic
breast cancer (cancer that has spread to other organs in the body, such as the lungs
or liver) within five years of their cancer diagnosis while the other 44 patients were
completely cancer-free after five years.
Using sophisticated genetic technology, the researchers were able to identify a pattern
of 70 genes that were only present in the women who went on to develop metastatic breast
cancer. According to van ‘t Veer, performing genetic analyses on breast cancer
samples obtained during breast biopsy or breast cancer surgery could help physicians
determine whether patients have aggressive or non-aggressive breast cancer and tailor
subsequent treatments accordingly. The results of the study were published in the journal,
Nature.
In accompanying editorial, Dr. Carlos Caldas and Dr. Samuel A. J. Aparicio of the
University of Cambridge in Britain expressed excitement at the possibilities the study
results raise. However, they also recommended viewing genetic analysis as only one
component when deciding on a patient’s cancer treatment.
van 't Veer and her colleagues believe that the next step in their research is to
perform the genetic analysis on a larger number of breast cancer samples to determine its
accuracy. The researchers point out that it took a year for them to conduct their study,
which is not a practical amount of time to perform a genetic analysis on a patient’s
breast cancer tumor.
Nevertheless, the study represents what many experts believe is the future of cancer
treatment: molecular genetics. Researchers have already made significant progress with new
"targeted" cancer drug therapies, which seek out and destroy cancer cells that
contain specific genetic components. For example, the drug Herceptin
identifies and destroys breast cancer cells that contain too many copies of HER2, a gene
that is associated with an aggressive-type breast cancer (approximately 30% of breast
cancer patients over-express the HER2 gene).
Presently, most breast cancer patients who undergo surgery are also treated with
chemotherapy, radiation, or drug therapy. While
these therapies have been proven to destroy remaining cancer cells, increase survival
rates, and/or reduce the chances of a cancer recurrence, they are also associated with a
number of unpleasant side effects. Dr. Caldas and Dr. Aparicio believe that if van t’
Veer’s genetic analysis could be performed on breast cancer tumor samples obtained
during surgery, only 25% of patients would need further treatment with chemotherapy or
other therapies (compared to between 70% and 91% who now receive additional treatments).
Until further scientific advances change breast cancer treatment guidelines, most women
will continue to undergo adjuvant breast cancer therapies. A panel of cancer experts
recently convened at the National Institutes of Health (NIH) Consensus Development
Conference on Adjuvant Therapy for Breast Cancer and made several recommendations
concerning adjuvant breast cancer therapies. Specifically, they recommended chemotherapy
for most pre-menopausal and post-menopausal women with localized breast cancer, regardless
of whether their cancer has spread to the lymph nodes or
has estrogen receptors. The panel also recommended hormonal drug therapy (most commonly
with tamoxifen) to women whose breast tumors contain
estrogen receptors, regardless of age, menopausal status, tumor size, or whether the
cancer had spread to the axillary (underarm) lymph nodes. Finally, the panel recommended
post-surgical radiation therapy for women who undergo mastectomy (surgical breast removal)
if they have large tumors or if four or more lymph nodes are found to be cancerous. Click here to learn more about these recommendations.
Additional Resources and References
- The study, "Gene Expression Profiling Predicts Clinical Outcome of Breast
Cancer," is published in the January 31, 2002 issue of Nature, http://www.nature.com/nature/
- "Cancer: The Molecular Outlook" by Carlos Caldas and Samuel A. J. Aparicio is
published in the January 31, 2002 issue of Nature, http://www.nature.com/nature/
- The November 7, 2000 Imaginis report, "Expert Panel Makes Recommendations about
Breast Cancer Treatments for All Women," is available at http://www.imaginis.com/breasthealth/news/news11.07.00.asp
- The January 30, 2002 Reuters Health report, "Gene Test Predicts Aggressive
Breast Cancer," is available within 30 days of publication at http://www.reutershealth.com/
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