Family history can be important for a number of cancers. You should therefore be sure to discuss occurrences of cancer in your family with your doctor. This is important among others for a number of gynaecological cancers such as breast and endometrial cancer. Intestinal cancer in the family can also play a role.
If the family situation suggests hereditary tumours, your doctor can discuss a genetic examination with you. This involves taking a blood sample to examine your genetic material or DNA for defects.
A number of genetic abnormalities can lie behind hereditary cancer. These include:
HNPCC or Lynch syndrome
Endometrial cancer, colon cancer and ovarian cancer occurring in families is observed with the so-called Lynch syndrome. A genetic abnormality in about six repair genes lies behind this problem.
In families with this HNPCC (hereditary non-polyposis colorectal cancer syndrome), except for colon cancer, endometrial cancer is the most common. Until the age of 70, 30% to 50% of women from HNPCC families develop an endometrial cancer, whereas the figure for the population in general is just 3%.
Where a gene mutation is proven, early detection by means of a transvaginal ultrasound is appropriate. Assessing the mucous membrane is more difficult with pre-menopausal women given the changes that occur during the menstrual cycle. If abnormalities are suspected, a tissue fragment is taken for examination.
Around 10% of ovarian cancers are caused by this. These hereditary variants occur an average of 10 years earlier than spontaneous tumours. Proven carriers are advised to have a periodic examination to enable the early detection of abnormalities in the ovaries.
BRCA-1 and BRCA-2
These two repair genes, BRCA-1 and BRCA-2, often contain defects relating to:
Hereditary breast cancer
A hereditary cause can be found with 5% to 10% of breast cancer patients. In half of this group, the tumour is caused by a defect in the repair genes BRCA-1 or BRCA-2. These defects may be passed on via the mother or the father. An abnormality is often found in the BRCA gene with hereditary ovarian cancer.
Hereditary ovarian cancer
In cases of hereditary breast and ovarian cancer where only the ovarian cancer occurs, this may be a variant, where breast cancer has not (yet) occurred in the family.
Carriers of a BRCA-1 gene mutation, the most common genetic cause of hereditary breast and ovarian cancer, have a 25% to 60% risk of developing ovarian cancer.
The risk of ovarian cancer for carriers of the BRCA-2 gene mutation seems to be around 20%.