On Jemma's 30th birthday, she decided to have her perfectly healthy stomach removed.

Jemma Caprioli was about to turn 30, and like any other woman approaching such a landmark birthday, she had many things to consider.

Would marriage and kids be on the cards in the coming years? Was her career going in the direction she wanted it to? Was she saving enough money for her future?

But the biggest question she had was, would she be alive to experience any of it?

So on the eve of her birthday, she sat down with her parents and her partner, David, and made the decision to have her perfectly healthy stomach removed.

Caprioli had an inherited mutation of the CDH1 gene, the precursor to an aggressive and rare gastric cancer that has killed 12 members of her family - one of them, at the age of 30. Before she had her stomach removed, she had an 80 per cent chance of developing the cancer, and was facing a 20 per cent survival rate if that cancer spread beyond her stomach.

From the age of 19, when she and her brother underwent genetic testing, and subsequently discovered they had the gene mutation they share with their mother, Caprioli was told she had three options.

To have her stomach removed, to do nothing, or have yearly gastroscopies and biopsies to monitor the cancer's progress. But that surveillance would not be foolproof.

"[Our gene mutation] is really rare, and they don't have too much knowledge around the subject. So for 10 years or so, I had gastroscopies where they put a scope down to look at the stomach, but they also take a biopsy from your stomach. That was the only method they had available as an option for us," the 30-year-old told Mamamia.

"Really the age factor was always on my mind, kind of like a countdown to 30 - we had a member of our family die at the age of 30 and really all we have to go on when you have a genetic mutation like ours is your family history. That can be quite tiring and wear on you because it's constantly a topic of conversation, and when you're doing the yearly endoscopies, it becomes front of mind again and again, and you're in a cycle that's not good for anybody, or your family.

"So as I was turning 30, I thought about what it would mean to have my stomach removed and for me to be able to have children in a couple of years time. I wanted to not have to worry about a) having the surgery at some point when I had a child, and b) if I would be strong enough to have children at all."

It was a ticking clock in a different kind of way to what most women feel. Because how do you reconcile what might happen with what might not?

"Your whole perspective shifts when you get news like [that you have a genetic mutation]. In reality, I came to the decision to remove my stomach quite quickly, over a few weeks. My parents came out for my 30th birthday and we talked about it, if it was the right time in my life where I felt supported in the right way. Work and my partner were very supportive, and my parents were very balanced, even though my mum had the surgery herself and it wasn't smooth sailing," she said.

"They both come from a medical background, so it's very hard for them because they know all of the bad things that could happen when you go through a major surgery. But mum especially didn't want to push me into any decision making. But also being a mother, she was very worried for her children.

"At the same time, it was hard to separate emotion from the decision making, because it was such an unusual situation to be in. It's not like you're feeling ill, or a doctor is saying you have to do this, and I thought, 'am I removing a body part that doesn't need to be removed?'. But it's so easy for you to ignore something that isn't a problem yet because you can't see it or hear it. My gastroenterologist, Professor Alex Boussioutas said to me that if it was his daughter, he would encourage her to have her stomach removed. It was heartwarming to have his honesty from somebody who has so much knowledge about genetic cancer and has seen so many people develop terminal cancer."

Three months on from the surgery to remove her entire stomach and attach the base of her oesophagus directly to her small intestine, Caprioli said everything hasn't fully sunk in yet. Including the discovery that two weeks post-op, early-stage cancer was indeed found in her removed stomach that had not yet spread through the stomach wall.

"I remember I was in hospital and a surgeon came to my bed and told me about my cancer in the pathology results and he said, you've made the right decision. In that moment, I felt a lot of relief. But also shock. Again, I didn't feel unwell [before the surgery] - you wouldn't feel unwell with such an early stage cancer anyway - but it is shocking, as it would be for anyone who has cancer, it's a very shocking moment in time."

While Caprioli is free from the anxiety that her stomach will harbour deathly cells at any moment, she now lives with a different reality: that of living with a chronic medical condition.

"Now I'm a completely new phase where I don't have to think about that risk anymore, but I now am living with a chronic condition. It's a journey, the first month was very very hard, and I would say the hardest thing has been my relationship with food now, and the relationship with my body," she explained.

"You do feel mentally challenged by the whole thing - for me, I was very much a foodie before, and I had the mentality that if you exercise you can eat as much as you want. I was big into exercising and eating really well before, and it's quite hard to get your head around it with before, being able to eat what you wanted, when you wanted, and however much you wanted."

She also feels the impact her condition has on her social life. When others order mains, Caprioli orders a starter. When they order wine, she sticks to water.

"Good food and drinking was such a big part of my social life. Coming from an Italian family it's challenging because I can't take on the same amount of carbohydrates as I used to. So that's a big one! And it's a different mindset, you have to be quite disciplined and strict with yourself. I also don't necessarily feel like I'm full most of the time, so I'll keep eating because I feel hungry, but then all of a sudden I feel full and I'll be sick. Your body does adjust, but it's still a bit confused about what's happening."

Caprioli's focus is now on moving forward with her life, moment by moment. In March, she'll compete in the Mount Kosciuszko Challenge, a 21-kilometre trek to the summit over 2,000 metres above sea level to raise awareness and funds with Rare Cancers Australia for the more than 52,000 people who are diagnosed with rare or less common (RLC) cancers every year in Australia.

Yes, her life is vastly different now. Essentially, Caprioli has swapped one condition for another. But she doesn't regret her decision, and wouldn't change it.

"I think about what it really means to be able to live your life day by day without having to worry about getting cancer. Every day is different, but I'm trying to take on every moment rather than think about it too long term, and be positive about everything.

"I didn't really feel like I could keep living my life in the way I wanted to, I needed to be the best version of myself at that point in time for my family and future, and that meant eliminating the risk."

You can support Jemma Caprioli and Rare Cancers Australia by donating to her Mount Kosciuszko Challenge. You can also find more information about rare cancers on Rare Cancers Australia's website.