Tomlinson was first diagnosed with cancer in 1990. After seemingly successful treatments, she was told in 2000 she had incurable, advanced metastatic breast cancer.
The disease spread, and was extensive. The prognosis was for her to survive just six months. Over a seven-year period, however, she endured numerous courses of chemotherapy and various drug regimes despite also developing chronic heart disease.
Defying doctors, she took on a series of challenges that were apparently impossible for someone with cancer who was undergoing chemotherapy treatment.
These included a full Ironman event, consisting of a 4km swim, a 180km bike ride and a full marathon, completed inside 17 hours; two half-Ironmans; the London marathon (three times) and the New York marathon; three London triathlons; and three long-distance bike rides: John O'Groats to Land's End, Rome to Home, and her final challenge, a 4,214-mile ride across the US.
Among the charities to benefit from her achievements are Sparks, which is dedicated to medical research into conditions affecting babies and young children, Macmillan Cancer Support and Martin House Children's Hospice, which provides care and support to families in which there is a child, or children, with a short life expectancy.
Tomlinson also raised money for paediatric acute services at Leeds teaching hospital NHS trust, where she became a radiographer, Bluebell Wood children's hospice, in Doncaster, and the US-based Damon Runyon Cancer Research Foundation, which aims to encourage young scientists to take on the challenge of defeating cancer.