Kim Niemi (right) is running Boston to support brain cancer research in an effort to help her friend Colleen Rommel (left).

About six years ago, Kimberly Niemi and Colleen Rommel met as many Hopkinton parents do — when their children started playing together and became friends.

Soon, the families, each with three young children, started spending more time together — especially the mothers.

“We developed a very close friendship,” Niemi said. “Our kids do a lot of the same sports, so we’re on the sidelines together. We do girls trips together, go to the beach together, our families go to Red Sox games and basketball games and other things together. So we have a special family friendship in addition to just the two of us.”

A year after the mothers met, Rommel started getting headaches. A visit to the hospital revealed a shocking and scary diagnosis: a type of invasive brain tumor called Grade 2 diffuse astrocytoma.

Surgery to remove most of the tumor was followed by chemotherapy and radiation treatments over the course of about a year.

“She handled it with the utmost strength, I think more than anyone could endure,” Niemi said. “She never complained.”

That strength inspired Niemi to take on a challenge that she had kept in the back of her mind for many years — running the Boston Marathon.

Niemi had thought about trying to run Boston since she was a student at Boston College and cheered on runners as they passed by the school. She has run a half-marathon and the Falmouth Road Race, but she took some time off when her kids were born.

“I had an itch to run the Marathon but never did,” she said. “After moving to Hopkinton, the itch came back. We watch it every year we’re here. The runners pass right by the top of our street. After my youngest was born, I took running up again. I’m a leisurely runner, very amateur, take my time, don’t go fast.”

After joining the online group Moms Run this Town, Niemi started training with three other mothers and made the commitment to run 26.2 miles.

“It just never seemed like the right year for me to run Boston, with young kids and then COVID and one thing after the next,” she said. “This year felt like the right year for me.”

Knowing she would not run a fast enough time to qualify, Niemi turned her attention to running for a charity.

“In thinking about charities that I would want to run for, the National Brain Tumor Society was front and center, pretty much the only charity that came to mind,” she said. “I reached out to them pretty early. The people there were so welcoming and warm and went to bat for me to get a bib.”

There are three other runners on the National Brain Tumor Society team — two survivors and one who lost a brother to a brain tumor — and the four have combined to raise more than $100,000.

“People are so generous,” Niemi said. “More people than I realized have been affected by brain tumors — people that I know, people that I don’t know. To know that someday we will be finding a cure because of the funds we’ve raised has been very rewarding.”

Rommel expressed gratitude for those who have helped fund research into developments to treat such cancers.

“I feel so very blessed to have friends like Kim who have supported me from day one through my cancer journey,” she shared. “I feel so lucky to have her in my life. Kim’s support along with my incredible husband, family and friends has given me the strength over the past 4 1/2 years to continue to fight this uphill battle. Like me, there are so many individuals out there who deal with the unimaginable diagnosis of brain cancer. The only way that we are able to survive is through the medical interventions required. These interventions are the results of research from the incredible doctors able to complete the research with the fundraising donations.”

While Niemi’s fundraising has gone well (givengain.com/ap/kimberly-niemi-raising-funds-for-national-brain-tumor-society), her training took a detour in late February when she had to have surgery to remove her gallbladder.

“I was in discomfort, couldn’t take a full breath, my running was horrible that week,” she recalled. A trip to the hospital determined she had an inflamed gallbladder, and she had it removed three days later. After returning home, she tried walking a mile outside, only to become dizzy.

“It was not a good walk. I was not sure how I was going to do the Marathon,” she said. After taking the next day off, she walked 3 miles and slowly returned to running.

“I’m fully recovered and running again,” she said. “I can’t believe I had surgery in the midst of all this. Also, at the very beginning of training, I had COVID. And [in late March] I was running on Hayden Rowe and took an awful spill — bruised, cut, the whole thing. But I just get back up and keep going. I have this goal in my mind and I’m going to get it done. I’m also thinking, this little blip pales in comparison to what someone with a brain tumor has to go through. I mean, I had laparoscopic surgery in my abdomen. It’s not like I had brain surgery, because that is just a whole other level.

“So I guess I’m realizing that A, I’m super grateful for my health and how my body has been able to recover, and B, it’s an unwavering commitment to the goal. I have the mental strength, and that’s been eye-opening to me, very rewarding and fulfilling.”