22/08/2016 09:23 BST | Updated 20/08/2017 06:12 BST

A Deadly Inheritance - Learning To Live With Hereditary Breast Cancer

It's March 2011. "I'm sorry, you have a BRCA1 mutation," says the Genetics Consultant. I'm not expecting this news. I start crying. I'm thinking about my daughter and my sisters. I feel like I'm to blame. How will I tell my family?

I'd been in the same consulting room a year before, a day after finishing chemotherapy, a lumpectomy and radiotherapy for a rare breast cancer. The Consultant had explained that all cancers are 'genetic' in that they arise from the action of damaged genes but only 5 - 10 per cent of breast cancers are the result of damaged genes - 'mutations' - which have been inherited. In the other 90 per cent or so of cases of 'sporadic' cancer, the damage in the gene occurs to cells across our lifetime, a so-called 'acquired mutation.' I wasn't surprised to be told I was at a low risk of having an inherited mutation as I had already been told I had no relevant family history twenty years previously. Although I wasn't eligible for genetic testing on the NHS, I could take part in research which would test for the BRCA1/2 while looking for other mutations.

Women with a BRCA1 mutation face a 60 - 90 per cent chance of developing breast cancer and around a 60 per cent chance of developing ovarian cancer. In the weeks that followed, I searched for positives - 'that explains why I got breast cancer,' and 'at least no one else in my family will have to go through cancer.' It was a long time before I appreciated my ongoing risk - just because I had already had breast cancer didn't mean I wouldn't get it again. In fact, I might be more likely to develop another cancer. I felt like a cancer-bomb.

I feel I'm supposed to say that the decision to have a preventative bilateral mastectomy was easy. It wasn't. I didn't want to have surgery. But, I reasoned, I didn't want cancer again either, so six months later, I went ahead with a bilateral mastectomy. A year later, my ovaries and fallopian tubes were removed.

Talking to other women and reading their accounts of how they'd felt, coped and the decisions they made was invaluable. Now the baton has passed to me to share what I've learned:

• Everyone has BRCA1/2 genes - it's mutations in these genes which can cause cancer.

• Mutations can be inherited from fathers as well as mothers (my mutation came from my father). As men have a 50-50 chance of inheriting a mutation, they need to consider their risk and the chance they might pass the mutation on to their children.

• Finding out you have an inherited mutation can feel like a life-changing moment, interrupting and consuming your life. You might be surprised by your feelings. There's no right or wrong way to feel.

• Having an increased risk of developing breast and ovarian cancer doesn't mean that you will definitely develop cancer. You have some difficult decisions to make but you don't need to make them straight-away.

• We don't yet know why some women with mutations develop breast cancer, others develop ovarian cancer and some never develop either disease. Our understanding of genetic risk is imprecise and evolving.

• Women with a BRCA1/2 mutation, and those at risk of developing inherited breast cancer, have two options: risk-reducing surgery or screening.

• How you choose to manage your risk is, I think, one of the biggest decisions you'll ever make. How did you approach other significant decisions in your life - where you live, your work? Do your research. Listen to your instincts.

• Ultimately only you can decide what's right for you. Family members might make different decisions, they might not even want to get tested - respect and support one another's feelings and choices.

• The needs of women who have already been diagnosed with breast and ovarian cancer differ from those of healthy individuals with a family history - knowing whether we have a BRCA1/2 mutation can inform decisions about the most effective treatments and how we manage future risk.

Following my surgery in 2012, cancer was discovered in the tissue removed from my other breast, a devastating discovery that meant more chemotherapy. This sneaky tumour hadn't shown up on any scans. I was lucky, risk-reducing surgery may have saved my life.

I didn't know my future held breast cancer. But what if you could change your high risk genetic inheritance? Information about inherited risk offers us the chance to change our genetic destiny, to alter our future. I've learned to feel empowered by this knowledge; it's meant I can manage my ongoing risk and give myself the best chance of living a long and healthy life.

Find Tamsin Sargeant at: Research Centre for Building Resilience in Breast Cancer

Breast cancer is the most common cancer in the UK, so even if a relative has had breast cancer, it doesn't mean you are likely to develop it too. If you are worried about your family history of breast or ovarian cancer, speak to your GP or a health professional.

Breast Cancer Care

Free Helpline 0808 800 6000 (Monday-Friday 9am-5pm, Saturday 10am-2pm)

The Royal Marsden NHS Trust Foundation (2013) A beginner's guide to BRCA1 and BRCA2

Friedman, S., Sutphen, R. and Steligo, K. (2012) Confronting Hereditary Breast and Ovarian Cancer, John Hopkins Press