Identical Twin Says Leaving Sister Behind Feels ‘Unthinkable’

Identical twin given six months to live – Caitlin Leggett, a 24-year-old woman from Cardiff, is confronting a life-altering prognosis after her leukaemia returned. The news has left her determined to seek a cure beyond the UK’s borders, driven by the emotional weight of being separated from her identical twin sister. “The idea of parting ways with her identical twin sister feels ‘unthinkable’,” Caitlin remarked, reflecting on the bond that has defined her life. Her journey began in April 2025 when a persistent rash became the first warning sign of her acute myeloid leukaemia (AML), a severe form of blood cancer affecting white blood cells.

The Twin Connection

While the sisters had always believed they were fraternal twins—because they developed in separate amniotic sacs—they were surprised to learn their DNA markers were identical after Caitlin’s diagnosis. This revelation came when doctors assessed Grace, Caitlin’s twin, as a potential stem cell donor, uncovering their genetic match. The discovery not only deepened their bond but also complicated Caitlin’s treatment. Grace, once a hopeful donor, was no longer an option due to the twins’ nearly indistinguishable genetic profiles.

A Struggle Against Time

Caitlin’s initial treatment included chemotherapy, which brought her into remission. However, in May 2025, her cancer resurfaced, prompting her to explore international treatment options. Her doctors noted that curative treatments in the UK were unlikely, leading Caitlin to pursue specialized therapies abroad—potentially in the US, where costs could exceed £500,000. The sisters, who have shared every moment since university, had always been inseparable, but now their lives hang in the balance.

Grace’s perspective on the situation underscores the emotional toll. “We’re only 24—nobody expects this to happen… Being twins, you’re not meant to have one of you not be there,” Grace explained. The twins’ close relationship, which began at university, has been a source of strength, but Caitlin fears their story might end before it fully unfolds. “We’ve gone through life together, and I don’t want our journey to end here,” Caitlin added, her voice steady but filled with resolve.

Unraveling the Diagnosis

Before her illness, Caitlin had ambitions of joining the Army and training as an intelligence officer after graduating in July 2024. She had scheduled a medical assessment for April 2025, but in March, a rash appeared that refused to fade with over-the-counter remedies. The symptoms prompted her to seek medical attention, culminating in a diagnosis at the University Hospital of Wales in Cardiff. Despite the absence of classic AML symptoms—such as pallor, fatigue, or unexplained bruising—Caitlin’s condition was confirmed through blood tests and a referral to the Teenage Cancer Trust unit.

Trials and Transplants

Following her diagnosis, Caitlin embarked on a treatment path that included two months of chemotherapy, leading to remission in May 2025. However, the cancer returned in August, necessitating a new approach. She participated in a clinical trial in Manchester using menin inhibitors, which temporarily halted the disease. A planned stem cell transplant in December 2025 followed, but the cancer resurfaced again just days before the procedure. After additional full-body radiotherapy, Caitlin achieved remission once more in January 2026. Despite this, her doctors warned that the treatment plan would only extend her survival by six months, prompting her to seek alternative cures.

Her current plan involves joining another drug trial for Bleximenib, with the hope that it will provide a more lasting solution. If this trial fails, there is a backup option available, though neither treatment is guaranteed to cure the disease. Caitlin’s case highlights the limitations of the UK’s donor network, as the NHS notes that over 2,000 people annually require stem cell transplants, yet only 7% of the eligible population is registered as a donor. This shortage of donors adds urgency to her decision to seek care abroad.

Hope on the Horizon

Caitlin’s family has rallied behind her, supporting her quest for a cure. The twins have launched a fundraising campaign to cover the costs of their international treatment, targeting £500,000 to finance options like CAR-T cell therapy in China or Singapore. While these therapies offer promising possibilities, they come with significant financial and logistical challenges. Caitlin’s resolve remains unshaken, even as she adjusts her monitoring schedule from monthly to quarterly bone marrow tests. “I wasn’t too happy about the change,” she admitted, but the extra test in May revealed the cancer’s return, reigniting her determination to find a solution.

Caitlin’s story is a testament to the power of family and the fight for survival. Her journey has not only tested her physical strength but also her emotional resilience. The twins’ bond, once a source of comfort, now drives her to overcome the odds. As she prepares for the next phase of treatment, Caitlin’s voice carries a blend of hope and urgency. “We’ve been through so much together, and I know we’ll face this as a team,” she said, echoing the strength that has carried them through their shared challenges.

A New Chapter

Caitlin’s experience with AML also sheds light on the broader issue of donor shortages. The NHS reports that while stem cell transplants are a critical treatment for blood cancers, many patients struggle to find a match within the UK’s registry. This scarcity underscores the importance of expanding donor networks and raising awareness about the need for participation. For Caitlin, the decision to seek care overseas is not just a personal choice but a necessary step in the fight for her life.

The twins’ story, once written in the context of university days and shared dreams, now takes on a new urgency. Caitlin’s battle with leukaemia has transformed their relationship into a symbol of hope and perseverance. As she looks toward the future, her focus remains on finding a cure that will allow her to return to her goals—whether that means joining the Army or simply continuing to share life with her sister. “I’m not giving up,” she said, her determination a beacon of hope in an uncertain journey.