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  Genetic predisposition for Breast and Ovarian Cancer

General Information

In Greece, 1 in 12 women will develop breast cancer and 1 in 70 ovarian cancer during her lifetime. It has been evident for many years that some families tend to have high frequencies of breast cancer.

If a woman belongs to a family that other members have been affected by these diseases, she is at very high risk for breast and ovarian cancer.

In these families, an individual is born with a mutation in a gene that predisposes to breast and ovarian cancer. The two most important genes are BRCA1 and BRCA2. Mutations in these two genes are thought to cause inherited breast cancer.

A BRCA1 or BRCA2 mutation can be inherited from either parent. When a parent has a mutation, there is a 50% chance of passing on the mutation to each of his or her children. Analysis of individuals with a family history of breast or ovarian cancer has revealed a plethora of mutations in the BRCA1 gene to date and more are being added.

Individuals who carry BRCA1 mutations have an 87% risk of developing breast cancer by age 70, compared to a risk of approximately 10% for non-carriers. BRCA1 mutations predispose a woman to a 44% risk of developing ovarian cancer by age 70, whereas non-carriers have a risk of about 1%.
Individuals with BRCA2 mutations have a similar breast cancer risk to BRCA1 mutation carriers and also are at increased risk for ovarian cancer, although this later risk is not as high as in BRCA1 carriers.
Women with a mutation who already have breast cancer may have up to a 65% risk of developing a second breast cancer.

Men who have a BRCA1 mutation do not seem to have an elevated risk for breast cancer, while men with a BRCA2 mutation seem to have a slightly increased risk (about 5-10%). The risks for prostate cancer in men and colon cancer in both men and women with a BRCA1 or BRCA2 mutation are also slightly increased.

Genetic Analysis of BRCA1/2

Scientists are now able to look for mutations in the BRCA1 and BRCA2 genes with a genetic test. This test analyses the mutations that might exist in BRCA1/2, and helps to determine if an individual has an inherited predisposition for breast or ovarian cancer. If a mutation is found, other family members might have inherited the same mutation and therefore have a high risk for cancer.
Identification of those who are at high risk for developing breast or ovarian cancer would gives us the opportunity to adapt the clinical management in order to facilitate early detection of cancer or optimal treatment for those already diagnosed with the disease.

The decision to have the genetic test

Genetic testing is a complex issue, and therefore it should be ensured that only those individuals for whom the results can be meaningful will be tested. Before you take the decision for getting the genetic test, it is essential that you discuss with your doctor or a genetic counselor about the steps you can take to try to prevent cancer from occurring or increase the chance that if cancer does develop, it will be detected early, when treatment is more effective.

The significance of knowing the result

If you have a relative with a known mutation, but you did not inherit the mutation, you are not at increased risk for cancer. It does not mean that you can never develop cancer, of course, but your risk would be the same as that of anyone else in the general population. If a mutation in BRCA1/2 is found, then the woman is in high risk for breast and ovarian cancer.
Also, other family members might have it. By knowing the result, the woman has the options to modify her lifestyle with the aim or reducing the chances of getting cancer. Also, the medical management of a woman with a known mutation in BRCA1/2 changes. The woman, in collaboration with her doctor, has the option to choose the diagnostic and therapeutic methods that are more suitable for her case. The aim is to facilitate early detection of cancer, offer optimal treatment for those already affected by the disease, or even reduce the risk of getting the disease.

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Related Links
·  Genetic Testing Update
·  Cancer Gene Anatomy Project: an interdisciplinary program to establish the information and technological tools needed to decipher the molecular anatomy of a cancer cell
·  What is the Human Genome Project? What's a genome? And why is it important?
To understand more about the science behind the Human Genome Project read The Science Behind the Human Genome Project: Understanding the Basics.
·  Genetic Odyssey: An Exploration of Genetic Topics
·  Understanding Gene Testing: a very good site explaining everything about genetic testing
·  Cancer Gene Anatomy Project: an interdisciplinary program to establish the information and technological tools needed to decipher the molecular anatomy of a cancer cell.