28/10/2016 07:02 BST | Updated 28/10/2017 06:12 BST

Kirstie Allsopp Chose Not To Have Mastectomy

Listening to Kirstie Allsopp talk about her family's cancer stories made it clear to me she had some real concerns about inherited cancer risk. Doctors suspect that there is a genetic link to cancer in her family, though they haven't discovered which, if any, genes are the cause.

In episode 4 of Stand Up To Cancer: The Podcast, Kirstie opened up about her own experiences. Sitting opposite her I could see how much her life and that of her family has been rocked by cancer, and just how determined she is to break out from under its shadow.

Listen as Kirstie opens up about her family's cancer story

It's worth saying at this point that most cancers are not inherited. If 1 in 2 people in the UK gets cancer, then you can see how an entire family could be affected purely by chance.

However, 'chance' isn't entirely accurate. There are things aside from genetics that can affect the risk of getting breast cancer - and these are both things that can't be controlled such as having children and breastfeeding.

We can alter things to help to reduce risk, such as keeping a healthy weight, regular exercise (perhaps jogging while listening to this podcast?) and reducing alcohol intake.

However, it's the inherited risk factors we discuss in this show. Like most cancers, breast cancer is more common in older people. If multiple family members develop cancers earlier than you would expect, say at middle age, then perhaps there really is an inherited gene at play.

Finding this gene is not straightforward. Some, such as the BRCA genes (pronounced Brakka) are easily tested for, but many others are still to be discovered. We have over 20,000 genes controlling our cells, providing them with the instructions they need to grow, move, feed, repair damage and millions more things. If a crucial gene is wrong from birth, it can dramatically increase your risk of cancer.

Mistakes in a gene can be subtle, and many won't cause cancer, so spotting an inherited cancer risk can be a big challenge.

In this case, Kirstie's higher risk is only suspected by doctors, but they had enough of a suspicion to offer preventative treatments. This offer led to her sister choosing to have a mastectomy and Kirstie choosing not to. I imagine that weighing up such a choice must be very hard, and so I hope that Kirstie's story will help others in a similar situation realise they are not alone.

Despite the difficulties, we are getting better at understanding cancer genetics. We're in the middle of a genetic revolution - doing things that were unthinkable even a few years ago. A simple cheek swab can now be the first step in reducing some people's cancer risk.

As our knowledge of genetics grows, we are beginning to design drugs that can actually play on the genetic mistakes that are the cause of cancer. This is real Achilles heel stuff that has the potential to take cancer down!

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If you'd like to Stand Up To Cancer with Kirstie and I, head over to the SU2C website for more information, donate or start fundraising. Join the rebellion against cancer!