Almost 2,000 women walked, jogged and sprinted around Leeds Road Playing Fields earlier this year to raise money to beat cancer.
But new figures reveal around 600 of the participants haven't paid in their sponsorship money yet to Cancer Research.
The hugely popular Race for Life in Huddersfield took place in Huddersfield in July - with the event being so in demand two races were organised, one in the morning and one after lunch.
But with the hundreds not handing in their sponsorship money, it means the charity is missing out on possibly up to £100,000 from the event.
Now Cancer Research UK is calling on Huddersfield’s runners to make every step count by paying in their sponsorship money as soon as possible.
Philippa Sharpe, Race for Life event manager for Huddersfield, said: “I want to say a heartfelt ‘thanks’ to everyone who took part in Race for Life, and their supporters, as well as our heroic volunteers.
Take a look below to see the runners in this year's race doing their bit in the fight against cancer in the gallery and video below.
“It was a fantastic day, full of emotion, courage, tears and laughter as over 1860 women joined forces to show cancer who’s boss.
“Now I’m asking all the women who took part - and all the friends, family and colleagues who pledged to sponsor them - to transform their passion into progress by returning the money they’ve raised as soon as possible.
“Cancer Research UK doesn’t receive any Government funding for its ground-breaking work. So every single individual contribution matters. It enables our researchers to help more men, women and children in Huddersfield survive this devastating disease.
“Many people don’t realise that their entry fee only covers the cost of the event. It’s the sponsorship money that really makes a difference. So, whatever the amount, we’re asking everyone to make every effort to return their sponsorship money as soon as possible. It can be paid in online, by phone or by cheque.”
Nell Barrie, Cancer Research UK’s Senior Science Communication Manager, said: “We want to see people with every type of cancer, including those that are hard to treat, get the same chances of living a long life. The progress made over the last 40 years shows we are moving in the right direction.
“As advances accelerate, our researchers are already laying the foundations for new ways to prevent, diagnose and treat cancer. These include personalised medicine where patients will have treatment tailored to their cancer, immunotherapy which harnesses the immune system to target the disease, better screening and tests to diagnose cancer earlier, and ways to help prevent the disease in people who are at risk.
“But each year more and more people are diagnosed with cancer, so there’s still much more to do. That’s why we need we need everyone who took part in Race for Life in Huddersfield to make every step count by supporting our doctors, nurses and scientists so they can take strides forward in the fight against this devastating disease.”