Identical twin given six months to live says leaving sister is 'unthinkable'

A woman given six months to live after her leukaemia returned says the thought of leaving her identical twin sister alone is "unthinkable".

Caitlin Leggett, 24, from Cardiff, was diagnosed with acute myeloid leukaemia (AML) - an aggressive cancer of the white blood cells - in April 2025, with a persistent rash the only sign that something was wrong.

She went into remission after chemotherapy and later had a stem cell transplant, but was told in May the cancer had returned and that treatment options in the UK were unlikely to be curative.

Caitlin is now pursuing potentially curative treatment abroad - most likely in the US - where treatment and associated costs could reach £500,000.

"We're only 24 - nobody expects this to happen... Being twins as well, you're not supposed to have one twin not be there," said Caitlin's sister Grace.

"It's unthinkable," Caitlin added.

"We've gone through life together and I don't want our story to end here."

The sisters, who have always been close and lived together at university, only discovered they were identical twins after Caitlin's diagnosis.

They had been believed to be fraternal twins because they developed in different amniotic sacs, but doctors found their markers were exactly the same while assessing Grace as a potential stem cell donor.

While the news came as a surprise, it also complicated Caitlin's treatment as Grace was no longer eligible to donate her stem cells to her sister due to their near-identical DNA.

Before becoming ill, Caitlin had planned to join the Army and train as an intelligence officer after graduating in July 2024.

She had a medical assessment booked for April 2025, but in March developed a rash which did not clear with pharmacy creams.

Blood tests were taken and she was told to attend the Teenage Cancer Trust unit at the University Hospital of Wales in Cardiff the following day, where she realised the news was serious.

While waiting to find an alternative donor from the register, Caitlin achieved remission in May 2025 after two months of chemotherapy. But in August, she was told the cancer had returned to her skin.

She later took part in a clinical trial in Manchester using menin inhibitors, which successfully put her into complete remission before a planned stem cell transplant.

However, a week before the transplant date in December 2025, the cancer returned to Caitlin's skin again.

She was still able to have the transplant, after receiving extra full-body radiotherapy and was told she was in remission once more in January 2026.

Caitlin was then scheduled for monthly bone marrow monitoring for three months, to check that the cancer had not returned.