Cancer Research UK is to emphasise the fundraising aspect of next year's Race for Life much more robustly than in previous years, in an attempt to ensure that all the runners send in their sponsorship money.
Much of the money pledged from the 162 Race for Life events held nationwide in May this year has failed to materialise.
For instance, nearly half those who took part in the Northampton race have failed to produce sponsorship cash. The 5km run was full to capacity and the most successful year in the race's history in terms of attendance.
But five months later, up to £60,000 has still not been paid.
The £8.50 entry fee covers the cost of the race, while any sponsorship money goes straight to research and treatment.
Nick Wright, race organiser, said: "Some people have probably not raised as much as they hoped or some have had trouble getting the money back in."
Wright also believes that some participants did not bother to raise sponsorship.
He explained: "I think there are some people who have taken part for the past few years and stopped collecting money because they think the entry fee is enough.
"Next year, we are pushing the message that Race for Life is a fundraising event and we need the sponsorship money."