Laura Davis was 25, the mother of a 3-week-old girl, when she was diagnosed with Hodgkin’s lymphoma. The immune-system cancer was aggressive, the symptoms debilitating, the diagnosis scary. She prayed she’d live long enough to watch her newborn daughter grow up.

With several operations and massive doses of radiation, Davis fought the lymphoma into remission. Ten years later, she was diagnosed with thyroid cancer. Seven years after that, it was basal-cell carcinoma – skin cancer.

She beat those as well.

Davis, who lives in Buckfield, credits the support of fellow cancer survivors for helping her through.

“This community that you never, ever want to be a part of, but once you are part of, is so supportive and just so amazing,” she said.

When the Maine Cancer Foundation proposed Tri For a Cure, a women-only triathlon to raise money for cancer research and patient support, Davis immediately signed up for the 12-mile bike ride, three-and-a-half mile run and a third-of-a-mile swim – despite the fact she was 44 and hadn’t exercised in almost a decade.

“I wanted to do it as sort of a personal challenge,” Davis said.

She isn’t the only one.

It’s just under a week away, and the Aug. 9 race in South Portland is already the Maine Cancer Foundation’s biggest first-time fundraiser ever. It’s proving to be one of the most popular and most profitable of any. All 550 race slots are full – many by women who have never done a triathlon – and another 500 have joined a waiting list in case any of the original athletes drop out. The foundation had hoped the triathlon would raise about $30,000.

It’s so far netted $155,000 in donations, not including major sponsorships and registration fees.

“We never could have predicted this in a million years,” said Joanne Jordan, special events manager for the foundation.

The Maine Cancer Foundation decided to hold Tri For a Cure after board members participated in a similar fundraiser in Massachusetts.

Sign-ups started in January. The foundation thought the race might be popular because it wouldn’t be highly competitive, would be open only to women and would fund Maine-based research of all types of cancer.

“But we had no idea it would sell out in eight weeks,” Jordan said.

Davis, a member of the foundation’s board and co-owner of Rinck Advertising in Auburn, was one of the first to sign up. Ten co-workers and family members joined her, including Sarah Irish, 19, the daughter who was 3 weeks old when Davis was diagnosed.

“I never thought I’d see my daughter graduate from high school, let alone run a triathlon with her,” Davis said.

To accommodate women who weren’t regular athletes, the foundation allowed participants choices: do the full triathlon (swim, bike, run), complete a duathlon (run, bike, run) or participate in only one leg as a relay team member. Davis will bike and run but will not swim.

She trains every day with her co-workers and family. She’s now able to bike 16 miles, four more than she’ll need for the triathlon.

“I think for every one of the athletes involved, it gives you a whole new perception of yourself. Like, ‘I’m an athlete? Really?’ And I am,” she said.

Davis has raised $2,400 in donations so far, making her one of the race’s top three fundraisers.

The race’s No. 1 fundraiser, Marianna Fenton of Cumberland, has raised $3,900. She’s determined to finish the race in memory of her 22-year-old stepdaughter, who died of cancer five years ago.

Like Davis, she’s never done a triathlon. In fact, she’d never run more than a mile.

Fenton cried with joy the first time she ran a three-and-a-half-mile loop in Portland. After training with other Tri For a Cure women, she can run over three miles and bike 14 miles.

“This is the hardest thing I’ve ever done willingly,” she said.

The race will begin at 8 a.m. at Southern Maine Community College in South Portland. For more information or to make a donation, go to www.mainetriforacure.com or call 773-2533.