Only one known person in the world can save my life

The world has a population of more than eight billion - but only one known person can currently save Sian Chathyoka, who has a rare blood cancer.

Sian, 56, said it was "very difficult to be upbeat" after being told last year she needed a stem cell transplant to survive, following a diagnosis of aggressive myelofibrosis. The mum-of-two was shocked to discover there was just one matching donor on the global register.

Sian, a former social worker, is now preparing to receive a transplant from a "selfless stranger" and has urged others to sign up to become donors.

Stem cell transplants offer "the last chance of life" for many blood cancer patients, according to the charity Anthony Nolan.

Sian, from Swansea, led an active lifestyle before becoming ill, including cold water swimming, running the family campsite and caring for her children, aged 18 and 13.

She first realised something was wrong when she was hit by "extreme fatigue" which left her struggling to get out of her chair.

"Since August, I've just been lying in bed because I've had no energy," Sian said.

"I've had such a level of fatigue, I haven't been able to do anything, and it's been quite scary."

When she noticed that she had lost 5lbs (2.3kg) without trying, Sian visited her GP and was sent for immediate blood tests.

"They came back and they were scattered all over the place," she explained.

Further CT and MRI scans revealed an enlarged spleen and, in September 2025, she was diagnosed with myelofibrosis.

"I couldn't stop crying," she said.

"My condition is very rare - I am the only myelofibrosis patient they've got in Swansea and Cardiff, and I've been told my disease is aggressive as well.

"When you take away the layers it's absolutely petrifying. But you've got to forget about that and be positive."

Since her diagnosis, Sian has been undergoing treatment to shrink her enlarged spleen and receiving weekly blood and platelet transfusions.

After learning a suitable donor had been found, Sian said she felt "lucky" and "grateful that there is the possibility of a cure through a stem cell transplant".

However, Sian said she was surprised by how little people knew about stem cell donation.

"A lot of my friends didn't have a clue," she said.

"That's why I want to raise awareness by sharing my story.

"Health is wealth and it is a luxury to be grateful for."

Stem cells are special cells that can change into other blood cells to be used to treat many different cancers, as well as immune deficiencies and genetic disorders, according to the NHS.

Most stem cells are donated by giving blood at a specialist centre, but in roughly 10% of cases they need to be extracted from bone marrow during a hospital procedure.

The Anthony Nolan and NHS Stem Cell Registry - which is formed of Anthony Nolan, DKMS UK, NHS Blood and Transplant, and the Welsh Bone Marrow Donor Registry - has more than 2.3 million registered potential stem cell donors.

The NHS says 30,000 potential new stem cell donors need to be recruited in the UK every year to meet demand.

Sian is now working with Anthony Nolan to encourage more people to sign up and "save a life".

"Just signing up to the register, you can literally save a life. I feel really emotional because that's as powerful as it is," she added.

Rowena Bentley, from Anthony Nolan, said Sian's story was helping to raise "vital awareness" of stem cell donation, adding that "becoming lifesaver ready is easy".