Researchers Identify New Gene that May be Related to Breast and Ovarian Cancers (dateline January 30, 2001)
In a new study published in the journal, Cell, researchers describe a newly discovered gene that may be linked to inherited forms of breast and ovarian cancers. The gene, BRAF35, has been found to interact with another gene, BRCA2 (breast cancer gene 2), which researchers have already tied to breast and ovarian cancers. When the genes are not functioning properly, they may cause cells to divide at an abnormal rate. It is estimated that between 5% and 10% of breast cancers are associated with genetic factors.
Ramin Shiekhattar, PhD of The Wistar Institute in Pennsylvania and the team of researchers report their discovery that BRAF35 somehow interacts with BRCA2 and can interfere with cellular repair. When the genes are mutated, they cause uncontrolled cellular growth, which leads to the development of tumors, according to the researchers.
While further research is needed, Dr., Shiekhattar says that this discovery provides researchers with new places to search for answers to their questions about the genetics of breast and ovarian cancer. BRCA2 and BRAF35 may be involved in both DNA repair and cell cycle progression, said Dr. Shiekhattar in a Wistar Institute statement.
Because approximately 80% of women who develop breast cancer have no identifiable risk factors (such as family history of breast cancer, early onset of menstruation or late menopause, etc.), researchers continue to investigate genetic and environmental factors that may contribute to the disease. In 1994, researchers discovered that women who carry mutations of BRCA1 (breast cancer gene 1) or BRCA2 are at higher risk of developing both breast and ovarian cancer than women who do not have these genetic mutations.
Changes in DNA can sometimes cause normal cells to become cancerous by de-activating the tumor suppressor genes. Researchers are still investigating how and why some genes mutate but have discovered that inherited DNA changes may cause cancers to occur more frequently in some families. However, most DNA mutations that cause breast cancer are not inherited; they occur during a womans life and may be caused by a variety of factors, many still unknown to medical experts. These factors may include exposure to certain chemicals (for instance, some pesticides, many of which are now banned, have been linked to cancer incidence), high dose radiation (from atomic bombs or from certain types of radiation therapy used to treat other cancers, etc.), other environmental exposures, diet, and smoking.
According to the Mayo Clinic, families that typically pass on BRCA defects have the following characteristics:
- Breast cancer in two or more close relatives, such as a mother and two sisters
- Early onset of breast cancer in family members, often before age 50
- History of breast cancer in more than one generation
- Cancer in both breasts in one or more family members
- Frequent occurrence of ovarian cancer
- Eastern and Central European (Ashkenazi) Jewish ancestry, with a family history of breast and/or ovarian cancer (researchers have identified two types of BRCA1 mutations and one BRCA2 mutation that are especially prominent in this group)
A genetic test is available to identify mutations of BRCA1 or BRCA2 genes. Because BRCA gene mutations have been associated with poorer outcomes (see article), women with one or more of the above characteristics may wish to consider genetic testing. However, this decision should be made carefully after consultation from physicians, family members, and a genetic counselor.
For women who test positive for genetic mutations that put them at higher than average risk of developing breast cancer, there are a number of options. These include close monitoring by physicians with clinical breast exams and mammography, taking the drug tamoxifen for a period of five years, or considering prophylactic mastectomy (preventive breast removal) in select cases. Women who are at high risk of breast cancer should talk to their physicians about these and other ways to help prevent or detect breast cancer at an early stage.
BRCA gene mutations also put women at higher risk for ovarian cancer. Ovarian cancer accounts for over 25,000 new cancer cases each year, making it the fourth leading cause of cancer deaths in women between the ages of 35 to 74, according to the National Ovarian Cancer Coalition (NOCC). Ovarian cancer is often called the silent killer because its symptoms can be subtle and overlooked, causing the cancer to be diagnosed in late stages when the chances of survival are much lower.
The following chart summaries some of the possible signs of ovarian and breast cancer. Women should consult their physicians if they experience these symptoms. However, because these symptoms can signal a number of conditions (many of which are benign), having one or more of these symptoms does not necessarily mean a woman has cancer.
|Possible Signs of Ovarian Cancer||Possible Signs of Breast Cancer|
- The report, "A Human BRCA2 Complex Containing a Structural DNA Binding Component Influences Cell Cycle Progression," is published in the January 26, 2001 issue of Cell. A summary of the report can be assessed after free registration on the website. The full report requires subscription to Cell. The Cell journal website is available at http://www.cell.com/
- The Wistar Institute is a National Cancer Institute Cancer Center. The Wistar Institute website is available at http://www.wistar.upenn.edu/
- The Mayo Clinic provides information on BRCA gene mutations and genetic testing at http://www.mayoclinic.com/home?id=HQ00350
- The January 26, 2001 Reuters Health report, "New Gene May Play Role in Breast, Ovarian Cancer," is available within 30 days of publication at http://www.reutershealth.com/archive/2001/01/26/morning/links/20010126elin029.html
- To learn more about genetic risk factors for breast cancer, please visit http://www.imaginis.com/breasthealth/genetic_risks.asp