In South Africa, a woman’s lifetime risk of developing ovarian cancer is about one in 82 and most breast and ovarian cancers occur only once in a family. However, some of these cancers can run in families. The presence of BrCa1 or BrCa2 gene mutation has been linked to increased risk factors of developing certain cancers.
What are BrCa1 and BrCa 2?
BrCa stands for: Br(east) Ca(ncer) susceptibility genes 1 and 2.
BrCa1 and BrCa2 are human genes that belong to a group of genes known as tumour suppressor genes. In normal cells these genes are responsible for maintaining a stable genetic environment. They also prevent uncontrolled cell growth such as occurs with cancers.
When these genes have undergone changes or mutations, they may no longer keep abnormal cell growth in check. These changes can be inherited or passed on from generation to generation.
Cancer Risk
Not all gene mutations or changes are harmful. Some may be beneficial and others may have no obvious effect. Harmful mutations can increase a person’s risk of developing a disease like cancer.
A woman’s lifetime risk of developing breast or ovarian cancer is greatly increased if she inherits a harmful mutation of BrCa1 or BrCa2. For breast cancer, a woman’s risk would be five times higher and for ovarian cancer 3-5 times higher and cancers in the breasts or ovaries of women with BrCa mutations are often at a young age.
The table shows the many cancers associated with BrCa mutations.
| BrCa1 | BrCa2 |
|
WOMEN |
|
| Breast | Breast |
| Ovarian | Ovarian |
| Cervix | Cervix |
| Uterine | Uterine |
| Pancreatic | Pancreatic |
| Colon | Colon |
| Stomach | |
| Gallbladder | |
| Bile duct | |
| Melanoma | |
|
MEN |
|
| Pancreatic | Pancreatic |
| Testicular | Breast |
| Prostate | Prostate |
| Colon |
Generally the incidence of BrCa1 mutations is between 1:500 to 1:800 people. The incidence of BrCa2 is even lower.
The incidence of BrCa1 and BrCa2 mutation in people of Ashkenazi Jewish descent is about 1:40. Certain families of Afrikaner origin may also be at higher risk.
It is estimated, based on statistics of white women in the USA, (South African statistics are not readily available) that inherited BrCa1 and BrCa2 mutation accounts for only 5-10 percent of breast cancers, and 10-15 percent of ovarian cancers.
Genetic Testing
There are blood tests to identify changes on the BRCA genes.
Test results take several weeks or longer and genetic counselling, by a health care professional experienced in cancer genetics, is usually recommended before and after such tests.
Such counselling services are available to private and state patients at:
Donald Gordon Medical Center,
Chris Hani Baragwanath Hospital,
Charlotte Maxeke (Johannesburg General) Hospital,
Reyhana Moosa (Coronation) Hospital.
Who should test for BrCa1 and BrCa2 Mutation?
The test is covered by some medical aid plans and costs vary from R3,000 to R10,000. There are no standard criteria for this but, if any of the following apply to you and your family, please consider testing.
Women who are not of Ashkenazi Jewish descent:
• Two 1st degree relatives (mother, daughter or sister) with breast cancer, one at age 50 or younger;
• Three or more 1st degree or 2nd degree (grandmother or aunt) relatives with breast cancer;
• Breast cancer and ovarian cancer in 1st and 2nd degree relatives;
• A 1st degree relative with cancer in both breasts (bilateral breast cancer);
• Two or more 1st or 2nd degree relatives with ovarian cancer;
• A 1st or 2nd degree relative with both breast and ovarian cancer;
• Breast cancer in a male relative.
Women of Ashkenazi Jewish descent:
• Any 1st degree relative with breast or ovarian cancer;
• Two 2nd degree relatives on the same side of the family with breast or ovarian cancer.
Benefits of Genetic Testing
There can be benefits whether a person has a positive or negative result. The potential benefits of a negative result include a sense of relief and the possibility that special preventative check-ups, tests or surgeries may not be needed.
A positive result can bring relief from uncertainty and allow people to make informed decisions about their future, including taking steps to reduce their cancer risk. People who have a positive test result may be able to participate in medical research that could, in the long run, help reduce deaths from breast cancer.
What are the Risks of Testing?
Risks are tied to the emotional, financial, medical and social implications of test results. Test results can affect personal choices such as marriage and childbearing. There are also concerns around possible discrimination for medical or life insurance policies as well as employment.
People who receive a positive test result may feel anxious, depressed or angry. They may choose to undergo preventative measures such as prophylactic surgery that have serious long-term implications and whose effectiveness is uncertain.
People who receive a negative test result may experience survivor guilt caused by the knowledge that they do not have the increased risk that their loved ones have.
What Do Negative Test Results Mean?
If a person tests negative an inherited increased risk of cancer associated with BrCa1 or BrCa2 is unlikely. Such a result is called a true negative. True negative results do not mean that a person will not develop cancer.
What Does a Positive Result Mean?
A positive result generally indicates that a person has inherited a known harmful mutation in BrCa1 or BrCa2 and therefore has an increased risk of developing certain cancers. A positive test provides information only about a person’s risk. It cannot predict whether an individual will develop cancer. Not all women who inherited a harmful BrCa1 or BrCa2 mutation will develop cancer.
Options after a Positive Test Result
Several options are available for managing cancer risk. High quality data and studies in the effectiveness of these options are limited.
Surveillance: this means screening for cancer to detect disease early. Screening does not change the risk of developing cancer. The goal is to find the cancer earlier, when it is most treatable.
• Breast cancer: clinical breast exams
• Mammograms
• Studies are underway to evaluate MRI (Magnetic Resonance Imaging) in women with BrCa1 and BrCa2 mutations
• Ovarian cancer: Clinical exams
• Transvaginal Ultrasound
• Blood tests for Ca125
Surveillance can sometimes find ovarian cancer at an early stage but it is uncertain whether this reduces a woman’s chance of dying from the disease
Risk Avoidance: certain behaviours have been associated with breast and ovarian cancer risk in the general population. Modifying individual behaviours to reduce risk has been poorly studied so far. Risk reducing behaviour would include: reduction in body fat, reduction in alcohol intake, reduced dietary fat intake, increased physical activity.
Prophylactic Surgery: this surgery involves removing as much of the high-risk tissue as possible in order to reduce the chance of developing cancer and includes: Bilateral prophylactic mastectomy (removal of both healthy breasts) and Prophylactic salpingo-oophorectomy (removal of healthy fallopian tubes and ovaries).
These procedures are classified as major surgery and do not offer a 100% guarantee against the development of cancer. Some tissue may be left behind and cases of breast, ovarian and primary peritoneal carcinomatosis (a type of cancer similar to ovarian cancer) have occurred even after prophylactic surgery.
For more information please contact: Division of Human Genetics, National Health Laboratory Services and University of Witwatersrand, Johannesburg, Tel: 011 489 9223/4 or email [email protected].
Written by Dr Sarah Rayne