Predictive genetic tests for cancer risk

Cancer isn’t usually inherited but some types – breast, ovarian, colorectal and prostate cancer – can be strongly influenced by genes and can run in families.

BRCA1 and BRCA2 are two examples of genes that raise your cancer risk if they become altered.

Having a variant BRCA gene greatly increases a woman’s chance of developing breast cancer and ovarian cancer and a man’s chance of developing male breast cancer and prostate cancer.

What to do if you’re worried

Speak to your GP if cancer runs in your family. They will refer you for an NHS genetic test which will tell you if you have inherited one of the cancer risk genes. This test is known as predictive genetic testing because a positive result means you have a greatly increased risk of developing cancer.

How the test works

A relative with cancer has a diagnostic blood test to see if they have a cancer risk gene. If your relative’s test is positive, you can have the predictive genetic test to see if you have the same faulty gene. If your test result is positive, it means you have a faulty gene that raises your risk of developing cancer. However, it doesn’t mean you will definitely get cancer.

To test or not to test

It’s a personal decision and knowing your results has advantages and disadvantages.

Advantages

You can take steps to manage your risk of developing cancer and knowing the result may reduce any stress and anxiety that comes from not knowing.

Disadvantages

Some results are inconclusive – doctors may identify a variation in a gene but not know what effect it may have. And some people would rather not know about their increased risk of disease and only want to be told if they actually develop cancer.