A genetic consultation is a discussion with a person trained in genetics. A genetic counsellor or consultant will listen to your concerns and advise you on your risk of developing cancer. They can also discuss possible ways of managing your risk. The meeting will last about 45–60 minutes. There probably won't be a physical examination, but you might decide, together with your counsellor or consultant, to see a doctor or breast nurse or to go for regular or one-off screening afterwards.

Screening means checking for early signs of the cancer or cell changes that happen before a cancer develops. There are different screening techniques for different types of cancer (see bowel cancer or breast & ovarian cancer risks).

Some people with a very strong family history of breast, ovarian, bowel, womb or pancreatic cancer are also offered a genetic test. You don't have to decide to have any test, or make any other decisions on the spot. You can take all the time you need to think things through. Then you can choose whether to have any tests, screening or any other options your consultant suggests.

You do not need to have a genetic test to have any screening that is available to families thought to be at high risk of developing cancer.

Genetic counselling is a two-way process. The better prepared you are, the more you will get out of it. You will also be better able to take part in the decisions that are made. The following questions might help you prepare for your initial clinic appointment:

• What are the names and ages of all your family members?
• What cancers did your relatives have?
• At what age were they diagnosed?

You also need some information about family members who have not had cancer: for example, their ages, and any serious illnesses they have had.

Some of this might be difficult – for example, if you have to speak to family members you haven't been in touch with for a long time. Talking about these issues might bring back painful memories for you or your relatives. Don't worry if you find it too hard, or impossible, to find out all the facts. Your counsellor will understand. There is also a cancer register where doctors can check which cancers people have died from, so they can use this to find out some of the information if necessary.

Your own family history will be very important in working out the chance of there being a genetic susceptibility to cancer in your family. It is a good idea to find out as much as you can about your family history of cancer. Before you attend your counselling session, you might be asked to draw a simple family tree, which shows all your close relatives and their respective illnesses (see example below).

It might be useful to write down a list of questions before you go to your consultation, to help you remember what you wanted to talk about. Here are some suggestions:

• What is my personal risk of getting a particular cancer?
• How sure are you about this?
• If there is a higher risk of cancer in my family, what are the options for screening or prevention?
• Are there any risks associated with screening?
• Is there anything else I can do to reduce my risk?
• Who else might be at risk in my family?
• What about children? Should they be told? Can they be tested?
• Do I need to tell everyone? How do I approach the subject?
• What if I am not at high risk of getting cancer? Will I get any follow-up?
• What if I want a test or screening, but it is not offered to me?
• Do I have to tell my insurance companies about my family history or about genetic tests?

Assessing your personal risk of cancer is difficult. Having a higher personal cancer risk means that you are more likely to get cancer than people in the general population. However, even if you have a cancer susceptibility gene, this does not mean that you will definitely get cancer. Most people who get cancer don't have one of the known cancer susceptibility genes.

Certain questions help to assess your cancer risk:

• How many of your relatives have been diagnosed with cancer?
• How old were they when they were diagnosed?
• How many relatives have not had cancer?
• Have there been any rare cancers or combinations of cancers in your family, such as male breast cancer, cancer in both breasts, breast and ovarian cancer or bowel and womb cancer?
• How old are you?

Assessing your cancer risk cannot show whether you will get cancer. Even if you are found not to be at an increased risk, you still have the same chance of getting cancer as the general population. Basically, everybody lives with some risk of developing cancer.

Assessing your risk of cancer might help you to decide what level of prevention and screening is sensible for you. For example, if you are found to be at a higher risk of breast cancer, you might be offered breast screening, such as x-rays of the breast (mammograms), at a younger age than people who are not at increased risk. If you are at significantly increased risk of bowel cancer, you will be offered bowel screening, where a thin flexible tube is inserted into your bowel in order to see inside (colonoscopy).

You will only be offered genetic testing if your family history makes it likely that there is a susceptibility gene for breast, ovarian or bowel cancer in your family.

The reason not everyone gets screening for all types of cancer relates to the benefits and disadvantages of genetic tests and screening. It is not simply about saving money.

Firstly, screening is not possible for all cancers. For example, there is no effective method of screening for pancreatic cancer. Mammography (breast x-rays) is the usual screening method for breast cancer and it doesn't work as well for young women (under 40 years). This is because their breast tissue is denser.

Secondly, there may be risks associated with a particular method of screening: for example, radiation. If we expose everyone to these risks, even if they do not have a higher cancer risk, we might be doing more harm than good. This is another reason why regular mammograms are not normally available to young women. If regular mammography started early in their lives they would be exposed to a higher amount of radiation over their lifetime.

Also, all tests can have misleading or false results, which can cause unnecessary anxiety before the results can be corrected or confirmed. It might be appropriate to risk this if doctors believe that someone has a higher risk of getting cancer, but it is not right to put the majority of people who are not at high risk of cancer through this.

Finally, because of the way genetic tests work it does not make sense to offer them to everybody. For the test to give meaningful results, scientists need to know which mutation they are looking for in a particular family or individual. This can normally only be done by testing a blood sample from a relative who has been diagnosed with cancer.