Dan Day, 27, will take part in the Polar Circle Marathon in Kangerlussuaq, Greenland, on October 28.
He is running in memory of Alex Bryant, who died in March 2023.
Mr Bryant, a lifeguard from Littlehampton in Sussex, was diagnosed with acute myeloid leukaemia (AML) in 2017.
In the following five years he had three stem cell transplants.
Mr Day said: “I always had the undeserved honour of a friend like Alex. He always held me accountable, always questioned why I didn’t take care of myself, always pushed me to strive for more.
“With everything that happened to Alex, it has helped me realise that I should, and absolutely can, help impact other people’s lives in a really positive way, and I see that as Alex’s enduring legacy.”
AML is a type of blood cancer which causes the bone marrow to make too many abnormal white blood cells and prevents it from making healthy blood cells.
All funds raised by Mr Day will go to stem cell transplant charity Anthony Nolan.
The marathon comes after he completed the Spartan Beast, a 21km obstacle race, earlier in October.
Mr Day added: “I’ve taken on these challenges because after hearing what Alex went through, there is nothing I can put my body through that can come close to that – and he did it all without complaining.
“If I can do something that can make even the smallest change to someone’s life, then it’s worth it. Alex was such a positive force and everything he did was so selfless, and he helped me realise that life is about helping other people.”
Kirsty Mooney, head of supporter-led fundraising at Anthony Nolan, said: “Fundraisers like Dan help raise crucial funds for Anthony Nolan, that not only help recruit new potential donors to the stem cell register, but also allow critical research to be conducted that can lead to new treatments.
“By undertaking a challenge like this, Dan is helping many other patients potentially have a second chance at life.”
Published: by Radio NewsHub
Written by: Radio News Hub