Five to ten per cent of cancers are hereditary. Genetic counselling assesses whether you or your family have an inherited predisposition, whether genetic testing is needed and which preventive measures apply to you.
What genetic counselling is
In most cases cancer is sporadic, that is, it happens by chance. In a small percentage, however, a mutation in specific genes is passed from generation to generation and explains why some families have many cases of cancer. People who carry such a mutation have a higher chance of developing the disease, often at a younger age.
Genetic counselling is a process with more than one meeting. The cancer genetics counsellor collects your personal and family history, estimates the likelihood of an inherited predisposition, and explains whether testing for mutations is needed and which preventive or therapeutic interventions apply to you.
Who needs genetic counselling
Not everyone does. It is usually recommended for two groups of people.
I have been diagnosed with cancer
I want to know whether there is an inherited predisposition, for me and for my relatives. Recommended especially when:
- the diagnosis was made at a young age
- I have had two or more cancers
- it is a rare malignancy, such as breast cancer in a man or medullary thyroid carcinoma
- there is a family history of the same or a related form of cancer
I have not been ill, but I am worried
My family history or another health condition increases the likelihood of an inherited syndrome:
- two or more close relatives with the same cancer, for example a mother and a sister with breast cancer
- the same or related cancers in many family members and many generations
- multiple bowel polyps or multiple skin lesions at a young age
- a known inherited mutation in a family member
How it works, step by step
- First session
Personal and family history, drawing of the family tree, clinical examination.
- Risk assessment
How likely an inherited predisposition is, the pros and cons of testing, which genes are worth testing.
- Genetic testing
A small blood sample, no fasting. The genetic material is isolated and analysed in the laboratory.
- Results
Within two to four weeks.
- Second session
Interpretation of the result, prevention plan, guidance for relatives.
How to prepare for the first visit
The assessment relies on the information you bring. Gather what you can about relatives up to the third degree, on both parents’ sides. Information about parents, siblings and children matters most.
What to bring with you
- For every relative with cancer: type of cancer, age at diagnosis, current age or age at death
- Copies of relatives' pathology reports, if available
- Your own medical history and your own diagnosis, if any
- Any known genetic test result, yours or a family member's
What the result means
Testing is followed by a second session, where your case is reassessed in the light of the result.
If you or your relatives are at the age of starting a family, the risks of inheritance and the interventions that may be needed beforehand are discussed in detail.
Support for you and your family
Depending on the case, genetic counselling and testing may also be needed for other family members, so that they receive personalised prevention guidance. The genetics counsellor and the collaborating psychologist help you manage the anxiety and fears that the information brings, and we discuss in depth the ethical and legal implications of a positive result.
Whenever needed, regular medical follow-up is scheduled for those in a high-risk group. The genetic counselling team remains available for any clarification, as often as you or your family need it.
The most common hereditary cancer syndromes
There are many hereditary cancer syndromes, some of them extremely rare. The best known are summarised in the table.
| Syndrome | Genes | What it causes |
|---|---|---|
| Hereditary breast and ovarian cancer (HBOC) | BRCA1, BRCA2 | Breast and ovaries in women. Breast and prostate in men. Increased likelihood also for pancreas and melanoma. The most common cause of hereditary breast cancer. |
| Cowden syndrome | PTEN | Multiple benign lesions of the skin, mucous membranes and gastrointestinal tract. Increased risk for breast, uterus, thyroid, bowel. |
| Lynch syndrome | MLH1, MSH2, MSH6, PMS2 | Colorectal or endometrial cancer, mainly at a young age. The Muir-Torre variant adds skin malignancies. |
| Familial adenomatous polyposis (FAP) | APC | A large number of polyps in the gastrointestinal tract from a young age and a strong predisposition to colorectal cancer. Requires very frequent surveillance or preventive surgery. |
| Li-Fraumeni syndrome | TP53 | Rare. Breast cancer, sarcomas, leukaemia, brain and endocrine gland tumours, from childhood to adult life. |
| Von Hippel-Lindau disease | VHL | Haemangioblastomas of the eyes, brain and spine. Adrenal and pancreatic tumours. Increased likelihood of kidney cancer. |
| Multiple endocrine neoplasia type 1 (MEN1) | MEN1 | Tumours of the pituitary, the parathyroid glands and the pancreas. |
| Multiple endocrine neoplasia type 2 (MEN2) | RET | Medullary thyroid carcinoma and phaeochromocytoma. |
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