A young woman has launched a campaign urging people to sign the stem cell register in a bid to potentially save her little sister's life.
Sofia Adamou, 22, from south London, said her world has been "turned upside down".
Her sister Natassa Adamou, 19, was diagnosed with chronic myeloid leukaemia (CML) earlier this year.
However, two weeks ago she was told her condition had progressed to acute lymphoblastic leukaemia (ALL), a rare type of cancer that affects the blood and bone marrow.
Sofia, who is working with stem cell charity Anthony Nolan, said: "You never think it's going to be you or your family until it is, and then it's like your whole world is just turned upside down."
The business owner from Anerley is currently waiting to see if she is a match for Natassa, but in the meantime has taken to social media to raise awareness of the stem cell register in case she is not.
"If I am a match, that would be the best thing in the world and I'll be able to save my sister's life," Sofia said.
"I am trying to get social media up and I'm trying to basically prepare. I know in doing this I'm not just helping my sister; I am helping many other people that are looking for donors."
The family, which includes mother Tina Adamou, 58, and father Adam Adamou, 57, have owned the Marlow Fish Bar on Marlow Road for more than six decades.
They have Cypriot heritage, so are also appealing for people in Cyprus to sign up as well as people in the UK.
People with heritage from different parts of the world can have different chances of finding a matching unrelated donor as they are more likely to have a rare tissue type.
Natassa - who Sofia describes as bubbly with a passion for theatre, reading and Formula 1 - was studying to be a make-up artist specialising in prosthetics and special effects when she started experiencing symptoms such as extreme tiredness and seizures around Christmas last year.
She was diagnosed with CLL, which was being treated with chemotherapy tablets until earlier this month.
Her disease must now be treated with chemotherapy and, ultimately, a stem cell transplant.
Speaking of her social media campaign, Sofia added: "Whether that helps my sister, or it helps someone else, it's important to do. Miracles can happen.
"You never know, you might have a friend that might be a match, and you never would have met that friend if it wasn't for something that you did in your life. Life has a very mysterious way of doing things."
Rowena Bentley, head of programme and community recruitment at Anthony Nolan, said: "Natassa's family are doing an incredible job in spreading the word about the stem cell register and Sofia is right, it only takes one person to sign up and potentially save a life like Natassa's.
"Our research shows that younger stem cell donors give patients the best chance of survival, that's why we're calling on healthy 16 to 30-year-olds to join the Anthony Nolan stem cell register.
"The more people we get on the register, the more matches we can make, and the more lives we can save.
"Signing up is easy, it's a quick questionnaire and a simple swab then you are lifesaver ready."
For more information, or to sign the register, click here: https://www.anthonynolan.org/help-save-a-life/patient-appeals/current-appeals/natassasmissiontoremission