Proceeds from a book by a young doctor – described as very brave and having left an extraordinary legacy – as he battled fatal skin cancer are to be donated to charity.

Mark Sims’ book is being published by his family posthumously after he died aged 28 on January 19 last year.

He began fundraising for Cancer Research UK from his hospital bed, with the aim of raising £1,000. The fund he started has now raised more than £200,000.

Dr Sims, who was originally from Bristol, was working as a junior doctor at St Helier Hospital in Sutton, south west London, when he was diagnosed with advanced skin cancer just before his 27th birthday.

His book, PS I Have Cancer, is the story of his 23-month wrestle with the disease, his mission to raise awareness and funds for research and how he unexpectedly found love while working through his bucket list.

Dr Sims died from malignant melanoma caused by a genetic fault, which has also affected other members of his family.

He was 15 when he was first diagnosed and was able to beat the disease. But in 2015, the disease returned and spread around his body, including to his lung, liver, spleen and gall bladder.

Dr Sims had an identical twin, Dave, 30, who is also a doctor, along with another doctor brother, Matt, 33, and Paul, 31, a teacher, who was diagnosed with skin cancer at a very early stage and managed to survive.

His father Chris, 61, has also had cancer caused by the genetic fault, along with his grandmother, Marion.

Another relative, an aunt, Julia, died of pancreatic cancer aged 56 as a result of the defective gene.

Dr Sims’ mother, Sue Sims, 58, has published the book through her own company, Poetry Space.

She said: “As soon as Mark knew that his time was running out he said to me: ‘Please publish the book for me, Mum. I know you’ll do a great job.’

“Over this past year, it has been a joy to work with Mark’s words and produce a book that I know he would be so proud of.

“The whole family has helped with proof reading which has been marvellous, a true labour of love from all of us.”

Dr Sims died at the Royal Marsden Hospital, London, where he had been treated throughout his illness with a targeted therapy followed by immunotherapy.

In 2016 he won the Cancer Research UK Flame of Hope Ambassador of the Year award for his work with the charity.

Lynn Daly, of Cancer Research UK, said: “As a doctor, Mark knew his time was limited the minute he was re-diagnosed with skin cancer.

“He wanted more than anything to make things better for future melanoma patients so he set about funding future research from his hospital bed.

“Mark achieved so much in two years under the very worst of circumstances. He was a very brave and generous man and has left an extraordinary legacy for which the charity is enormously grateful.”