Mrs Fish, who died last month at the age of 87, helped found the Doncaster Cancer Detection Trust nearly fifty years ago and helped raise more than £10 million over the years.
Sunday's Mid Summer Scanner Walk is the first major fundraising event since her death of May 2 and organisers are looking for a good turnout for people who want to pay tribute.
Barry Goforth, secretary of Thorne Rural Lions, one of the organisers of the event, which starts and finishes on Town Field, said: "It is very important to us all we have a good response in the memory of Jeanette..
"We want as many walkers and sponsors to be involved, take part or donate towards the scanner appeal to benefit us all."
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The 10k walk around Doncaster sets off at 10am and fancy dress is optional. Funds raised will go towards a £1 million appeal to buy new scanning facilities at Doncaster Royal Infirmary.
Contact (01302) 536472 for entry details.