Many women may have a family history of breast cancer in a blood relative. Most of this is just a coincidence. On the other hand, some rare women may have more than one breast cancer relative from the same blood line, either on the maternal or paternal side. In this case, it is possible for the women of the family to carry a defective gene that causes breast cancer in the long term. This condition, called familial breast cancer, is responsible for only 5% of all breast cancers. Evaluation of the current risks by blood tests of all women from families carrying this defective gene is important in terms of preventive medicine.
Not every woman with a family history of breast cancer falls into the familial breast cancer group. Having more than one breast and ovarian cancer in the same branch of the pedigree, being diagnosed with breast cancer before the age of 40, and being seen in men in the family should always bring to mind familial breast cancer.
It is known that the reason for this is the defect of some genes in families with very frequent breast cancer. For the diagnosis of familial breast cancer, it is necessary to look for defective genes that cause breast cancer. There may be different gene disorders that increase the risk of breast cancer, but two of these have been fully demonstrated and put into clinical practice: it is currently possible to study patients’ BRCA1 and BRCA2 genes. Not everyone who tests positive for these genes will get breast cancer. If one of these two genes is found to be defective, the patient’s lifetime risk of developing breast cancer is eighty-five percent. Half of women who carry the defective gene will develop breast cancer by the age of 50.
This test should be applied to the patient who has been diagnosed with breast cancer and who suspects that this cancer may be “familial breast cancer”. If the test is positive in this person, that is, it is determined that the family has a genetic predisposition, all the women of that family are examined with these tests. Women or girls who are BRCA1 or BRCA2 negative have the same risk of breast cancer as the population, while those with a positive test mean a high risk.
Women with familial risk of breast cancer should definitely be enlightened in terms of more intensive breast follow-ups and breast cancer preventive treatments.
