Researchers are investigating whether performing a special genetic test on breast cancer tumors removed during surgery can help determine which women should receive chemotherapy as part of their treatment. Presently, approximately 90% of American women and 70% of European women undergo chemotherapy after surgery to help prevent a recurrence of breast cancer even though the majority of these women will not develop the disease again. Though their research on the genetic components of breast cancer recurrence is preliminary and significant study and clinical trials are still needed, the researchers believe that a test to determine which breast cancer patients do and do not need chemotherapy could possibly be available in five years.
Chemotherapy involves treating patients with anti-cancer drugs. It is a systemic treatment, meaning that it can destroy cancerous cells throughout the entire body (compared to a local treatment such as radiation therapy that targets only one area of the body). While chemotherapy can be a very effective treatment for breast cancer, particularly at preventing a recurrence of the disease, it can also be associated with several side effects. Though side effects vary depending on the drugs and dosages, the most common side effects of chemotherapy experienced by breast cancer patients include fatigue, nausea and vomiting, and hair loss.
According to Dr. Bruce Ponder of Cambridge University in England, it is a known fact that some women who undergo surgery for breast cancer will experience a recurrence of the disease within five years. Therefore, women are often treated with chemotherapy after surgery to help prevent a recurrence. However, if physicians could determine which women were at a high risk of a recurrence, they could reduce the number of women who are given unnecessary chemotherapy.
This was the purpose of a study conducted by lead researcher Laura van ‘t Veer, a pathologist at The Netherlands Cancer Institute in Amsterdam, and her colleagues. The study was presented at the recent conference of the European Federation of Cancer Societies in Lisbon, Portugal. Dr. van ‘t Veer studied the activity of 25,000 genes in breast tumors of 78 patients who underwent treatment for breast cancer between 1983 and 1995. Most of the women in the study did not receive chemotherapy because it was not the standard treatment after surgery at that time. Specifically, Dr. van ‘t Veer was looking for which genes contained a specific molecular makeup that signaled that cancer cells had spread out the breast to other areas of the body (since these patients would be a high risk for a breast cancer recurrence).
In the study, 34 of the women experienced a recurrence of breast cancer while 44 of the women did not. Dr. van ‘t Veer was able to find a unique signature in the tumors that had spread out the breast to other areas of the body among the patients that experienced a cancer recurrence.
According to Dr. Ponder, the study shows that genetic testing on breast tumors holds promise and could eliminate the need for chemotherapy for many breast cancer patients because each treatment plan could be tailored to each patient’s genetic test results. In fact, at the conference presentation, researchers estimated that the number of women who are given chemotherapy unnecessary could be reduce from 90% of American women and 70% of European women to approximately 27% of women overall.
In the United States, most women who have breast cancer tumors that are over one-half inch in diameter receive chemotherapy in addition to breast cancer surgery. In Europe, women whose tumors are over one inch in diameter, are over age 35, and whose tumors are not dependent on the hormone estrogen for survival are usually given chemotherapy in addition to breast cancer surgery. Women whose tumors are considered aggressive are also typically given chemotherapy.
It is estimated that approximately 20% to 30% of women with early-stage breast cancers experience a recurrence of the disease within five years. As this preliminary research on the molecular makeup of breast cancer tumors becomes more substantiated, more treatments can be tailored to individual patients based on genetic test results, potentially reducing the chances of cancer recurrence.
- The study, "Low Penetrance Susceptibility Genes for Breast Cancer," was presented at the conference of the European Federation of Cancer Societies October 21 through October 25, 2001. An abstract of the study can be found at http://www.fecs.be/Conferences/ecco11/index.shtml
- The October 24, 2001 Associated Press report by Emma Ross is entitled, "New Genetic Breast Tumor Test Noted."
- To learn more about chemotherapy, please visit http://www.imaginis.com/breasthealth/chemo.asp
