Hereditary breast cancer Private lecturer Dr. med. Eva-Susanne Strobel is chief physician of the “St. Georg Vorsorge- und Rehabilitationskliniken”, being specialist in internal medicine, notably in haematology, internal oncology and rheumatology as well as in the additional fields of social medicine, rehabilitation and physical therapy.
Breast cancer is the most frequent oncological disease among women. Annually about 43.000 women are affected by breast cancer.
The development of a breast cancer is rather uncertain. It depends in particular on the stadium of the disease and on the level of proliferation at the moment when the disease is detected.
If a breast cancer is diagnosed in an early stadium, the healing chances are much higher. Each woman can contribute to an early detection by undergoing regular medical check-ups additionally a periodic mammography from 40 years on.
The age of the patient plays also an important role. If breast cancer occurs in young women, it grows generally faster than it does in a seventy year old woman. The breast cancer concerning young women has further singularities. It might indicate to a hereditary predisposition to develop cancer. Less than one percent of the cases of breast cancer occur between 20 and 30 years; however, more than 50 percent of breast cancer cases under the age of 30 years are deemed to have hereditary causes.
Most of the breast cancers occur sporadically. Only in five up to 10 percent at maximum they are due to a genetic (hereditary) predisposition. The causes are mutations or alterations of different genes. In recent years research has generated many new findings in this field and we have learned much about the genes BRCA1 and BRCA2. BRCA stands for breast cancer. BRCA genes are tumour suppressing genes; this means they impede normally the development of cancer. However, if the breast cancer genes BRCA1 and BRCA2 undergo a mutation, they can be co-responsible for the development of breast cancer or other tumours. Mutations of the genes BRCA1 and BRCA2 cause 60 to 70 percent of these hereditary breast cancers.
The fact, that a mutation of breast cancer genes BRCA1 and BRCA2 occurs, doesn’t mean that cancer develops inevitably; however, the probability of being affected by cancer is then much higher. A mutation of the BRCA1 gene leads to a 50 to 60 percent risk of developing breast cancer until the age of 70 years and to a risk of about 16 percent of developing an ovarian cancer until the age of 70 years. Among men it increases the risk of prostate cancer. A mutation of the BRCA2 gene increases the risk of both female and male breast cancer on a similar scale. Even ovarian, prostate and pancreas cancer develops more frequently.
In about 50 percent of the women affected by mutations of the BRCA1 or BRCA2 gene, the breast cancer occurs before the age of 50 years, affecting frequently both breasts.
There are various mutations of the BRCA1 and BRCA2 genes, representing different risks of developing breast cancer and a different incidence of ovarian cancer.
BRCA1 mutations have an incidence of about 1 per 1000 among the population. In Germany, new mutations occur frequently; this means that different patients may be affected by different mutations. Among other peoples, such as Icelanders, Norwegians, Swedish, Finnish and Dutch the same mutations can occur in different patients.
In what case is it reasonable to verify a mutation of the BRCA1 or BRCA2 gene?
The “Deutsche Krebshilfe, Mildred-Scheel-Stiftung” (German cancer society, “Mildred Scheel” foundation) is conducting a research project concerning the hereditary mamma and ovarian carcinoma (hereditary breast and ovarian cancer). The research project of the “Deutsche Krebshilfe”, which started in 1996, consists in the study of the mutations of the BRCA1 and BRCA2 gene within concerned families. First the affected patient is examined in order to determine whether there is a mutation. If a mutation is detected, other members of the family are examined subsequently so as to verify whether they are also affected by the mutation. Thanks to these genetic examinations it is possible to find out, even before the outbreak of the disease, those men and women of the concerned families presenting a particularly elevated risk of breast cancer and of other tumours. So these healthy persons can benefit from an early check-up program.
The examined persons are accompanied before and during the genetic diagnosis by an interdisciplinary team of gynaecologists, geneticist and psychologists.
A genetic diagnosis of mutations of the BRCA1 and BRCA2 genes is only reasonable when there is a certain probability of detecting a hereditary breast cancer for the following reasons:
Definition of the risk factors for hereditary breast cancer
- at least two members of the family suffer from breast cancer, one of whom aged less than 50 years
- or at least two affected members of the family, one of whom suffering from ovarian cancer before the age of 50 years and one of whom suffering from breast cancer regardless to the age
- or a case of breast cancer affecting both breasts or of male breast cancer
- or a case of breast cancer before the age of 30 years
The early check-up program cannot prevent the breast cancer but it aims at detecting the disease in an early stadium, when it is still curable. The early breast cancer check-up program for high risk patients with BRCA1 or BRCA2 mutations includes the following examinations:
- self-examination of the breast; manual examination of the breast by the physician
- ultrasound examination of the breast
- mammography
- magnetic resonance imaging of the breast
The self-examination of the breast should be done monthly and the manual examination of the breast by the physician should be carried out every six months. The ultrasound examination should also be executed half-yearly. The basic mammography ought to be executed at the age of 30 years of five years after the first case of breast cancer in the family. If the mammography provides good results it should be repeated annually. The mammography allows the diagnosis of a breast cancer already at a size of only one or two millimetres. The density of the mammary gland tissue of young women may impede the diagnosis of a cancer by means of mammography. The growth rate of breast cancer in young women is generally also higher than among older women. Given this fact, the efficiency of the early check-up program by a mammographic examination is diminished. The magnetic resonance imaging of the breast should be carried out annually until the age of 50 years. Afterwards it is only necessary if the mammographic results are uncertain.
Since the occurrence of ovarian cancer is more frequent among women with mutations, the diagnosis of this disease has to be included in the early check-up program. The early ovarian cancer check-up program for high risk patients with BRCA1 or BRCA2 mutations shall include a half-yearly gynaecological ultrasound examination through the vagina and additionally a measuring of the Ca-125 level in the blood for women beyond the menopause.
Summary:
The positive conclusion, which we can draw from these facts, is that we are now able to find out by means of a genetic analysis, whether a person presents a higher risk of developing breast cancer. The genetic analysis allows moreover to find out those persons who have relatives suffering from breast cancer, but who don’t present a higher risk of breast cancer because they are not affected by any mutation. These women can be relieved by the genetic examination, being assured they don’t have mutations.
Persons with a BRCA1 or BRCA2 mutation may benefit very much from a thorough early check-up program, which gives hope for recovery since it helps to detect cancer in such an early stadium. Thanks to these newly conceived diagnostic methods cancer isn’t any more so scaring.
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