Family and cancer risk

Lesley: I’m Lesley, I’m 37 and my sister Sarah had breast cancer in her early 40’s. It did cross my mind at the time when it was happening whether that I would have an increased chance of getting breast cancer. Katie: If someone in your family is diagnosed Show more

with cancer, it’s normal to wonder whether you might be at increased risk of developing cancer. Cancer is unfortunately very common and over 1 in 3 of us will develop cancer in our lifetime. To help understand how cancer runs through families, it’s important to understand a little bit about how genes are passed on. Our bodies are made up of tiny building blocks called cells and within each of our cells is the entire genetic code which gives our bodies instructions of how to work and function properly. We have 2 copies of all our genes because we get one copy from our m and we get one copy from our dad. I always imagine that when the sperm and egg come together to make a fertilised egg that egg has to contain the entire instruction manual of how to make a human being and keep that person working for the rest of their lives. A gene Show more

is an instruction for a specific part of us, so we have genes that tell us what colour our eyes will be and some of our genes protect us from getting cancer. This means if we have a mistake in one of those genes, it can increase the chance of a cancer developing. This is known as a gene mutation. Some gene mutations occur in that very first fertilised egg and are present at birth. They’re in every cell in the body and they can increase the chance of a person developing cancer in their lifetime. And those are the types of cancer genes that run through families. That’s known as a heritable genetic mutation. It’s actually very rare for a person to be born with a gene mutation in a cancer gene that’s increased the chance of cancer developing in their lifetime. For the vast majority of cancers, the genetic changes that have caused the cancer, occur just in a single cell. For example, a cell within the breast, that develops a mistake, that then goes on to become a cancer. This is known as an acquired mutation. So how do we try and decide if a person might have an increased risk of developing cancer because of genetic changes? We can look at the ages that people have developed cancer. We can look at the number of people who have developed cancer in the family and how closely related those people are. We can look at whether a person has developed more than one cancer. For example, having two separate breast cancers might indicate an increased genetic risk. And we can also look at the type of cancer as well and whether those cancers in a family might be linked to a certain genetic cause. Lesley: The doctor took a full family history and because she’s over 40 and because there’s no other history of anyone in our family having breast cancer, they said we didn’t need any further screening. And I did feel reassured by that. Katie: For Lesley, we wouldn’t need to recommend any other screening or genetic testing other than that which we would offer to all women in the population. However, we would however advise Lesley to get back in touch if there were any new diagnoses in herself or a relative, as that may change our recommendations. If you are worried about the pattern of cancer in your family then please go and talk to your GP. Your GP will be able to ask you about Show more

your family history and if they feel you need further assessments can refer you a family cancer clinic or to a cancer genetics unit. If you don’t have a very strong family history of cancer, then in most cases your GP won’t need to refer you onwards. In those cases, you should still bear in mind all of the lifestyles factors that could increase the risk of cancer such as making sure you’re not smoking, keeping to a healthy weight and under taking regular exercise. Show more

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