Cancer is a group of diseases in which cells in the body grow, change, and multiply out of control. By definition, breast cancer begins as an erratic growth and proliferation of cells in the breast tissue. After these cells have formed a tumor in the breast, some of them may break away and spread (metastasize) to other parts of the body. While cancer has the potential to spread to any region of the body, researchers are beginning to understand why breast cancer is "attracted" specific areas, such as the lymph nodes, lungs, liver, and bone marrow. In a newly published study, scientists were able to use this knowledge to prevent breast cancer metastases in mice. They hope their findings will lead to significant discoveries that could eventually help to prevent metastatic breast cancer.
The research was conducted by Dr. Albert Zlotnik and his team of scientists from DNAX Research Institute in Palo Alto, California. According to the researchers, proteins called chemokines are key in understanding how breast cancer spreads to other body parts. Normally, chemokines play a role in telling cells where to go. However, the researchers found that cancerous tumors contain chemokine that attracts them to specific areas of the body with compatible chemokine receptors. In the case of breast cancer, the lymph nodes, bone marrow, lungs and liver contained these compatible chemokine receptors.
Using this knowledge, the scientists conducted studies on laboratory mice. After injecting the mice with human breast cancer cells, an antibody was used to prevent the chemokine in the cancer cells from binding to the chemokine receptors in the lungs. Thus, the scientists were able to reduce the number of lung metastases in mice, with some mice not developing any lung tumors at all.
According to Isaiah Fidler, DVM, PHD, BS, Chairman of Cancer Biology at M.D. Anderson Cancer Center in Houston, Texas, this research is very exciting and may lead to major discoveries concerning metastatic breast cancer. However, Dr. Fidler also cautioned that chemokines may only be one factor in breast cancer metastases, and that several factors likely play a role in determining how cancer cells spread to other areas of the body.
In an accompanying article published in the journal, Nature, Dr. Lance Liotta, a pathologist with the National Cancer Institute, outlines three theories that may explain why breast cancer tends to spread to certain organs:
- Chemokines play a role, as the DNAX researchers found in this most recent study
- Tumor cells only multiply in organs that contain certain growth factors
- Cells lining blood vessels in certain organs express molecules that prevent cancer cells from multiplying in those organs
While the research is promising, it is preliminary and still needs extensive study. The researchers are also unsure whether they would be able to reproduce the promising results they saw in mice studies with humans. However, the research does appear to be an encouraging first step toward a better understanding metastatic cancer. The researchers are already investigating whether they can prevent the spread of melanoma using this knowledge of chemokines. Melanoma is a type of skin cancer that appears to spread in a similar fashion to breast cancer.
Metastatic breast cancer is a Stage IV, advanced cancer in which breast cancer has spread past the breast and axillary (underarm) lymph nodes to invade other areas of the body. In 10% of breast cancer diagnoses, the cancer has already spread to distant organs in the body. According to the National Cancer Institute, approximately 10% to 20% of women with metastatic breast cancer survive the disease (achieve permanent remission). However, advances in treatment options are providing women with metastatic breast cancer with better comfort and longer survival times.
- The study, "Involvement of Chemokine Receptors in Breast Cancer Metastasis," is published in the March 1, 2001 issue of Nature. The accompanying article by Dr. Lance Liotta, "Cancer: An Attractive Force in Metastasis," is published in the same issue. The full text articles are available for a limited time on the Nature website at http://www.nature.com/nature/
- The National Cancer Institute provides information on breast cancer at http://cancernet.nci.nih.gov/
- The February 28, 2001 Reuters Health report, "Chemokines Determine Breast
Cancer Metastatic Destinations," is available within 30 days of publication at http://www.reutershealth.com/cgi-bin/frame2?top=/tops/med.html&lef
t=/medl.html&right=/archive/2001/02/28/professional/links/20010228scie001.html - The February 28, 2001 Associated Press report, "Scientists Gain Breast Cancer Facts," is available within 30 days of publication on Yahoo at http://dailynews.yahoo.com/h/ap/20010228/hl/cancer_s_spread_1.html
- To learn more about metastatic breast cancer, please visit http://www.imaginis.com/breasthealth/metastatic.asp
