LEWISTON — Nearly 3,000 runners and walkers stepped off for treks of 5 kilometers and 10 kilometers through the Twin Cities on Saturday morning as the seventh annual Dempsey Challenge opened at Simard-Payne Memorial Park.

Patrick Dempsey, actor, auto racer and Lewiston native, was once again at the center of the weekend celebration of cancer survival and tributes in memory of loved ones lost to the disease. He greeted fans one on one with boundless enthusiasm, posing for endless selfie opportunities with his admirers, mostly female.

The event is a heartfelt and fun-filled approach to dealing with cancer. The Patrick Dempsey Center for Cancer Hope & Healing is the beneficiary of money raised by participants. The center provides free support, education and wellness services to anyone affected by cancer.

Dempsey was joined this year by Joan Lunden, a respected journalist and TV host who was diagnosed with breast cancer in 2014. They shared stage duties Saturday morning and led the annual Cancer Survivors’ Walk.

Hundreds of survivors took part in the march around the park. They were led by the Red Eddies Marching Band of Edward Little High School in Auburn. Among the walkers was a 39-year survivor and numerous members of her family.

Also addressing the crowd was Dr. James Campbell, who is the Amanda Dempsey Award winner. He is a two-time melanoma survivor and is a practicing dermatologist in New Hampshire who champions early detection and cancer prevention. Amanda Dempsey, Patrick’s mother, died last year of ovarian cancer and was the catalyst for the actor to establish the center.

From sunrise Saturday, it was apparent that the 2015 Dempsey Challenge would be a crowd-pleaser. Bright sunshine quickly raised chilly morning temperatures, and the two celebrities served as starters for the run/walk events. Many participants were dressed in whimsical costumes, and most wore T-shirts identifying team fundraising efforts.

All ages took part in the run/walk. Some older people were in wheelchairs, and many toddlers covered the course in strollers pushed by their parents.

Melissa Cooper and Meg Chase led a group of several marchers who called themselves “Richard’s Army.” They took part in the Dempsey Challenge in memory of Richard Dulac of Lewiston, who died of melanoma in 2013.

Cooper said the Dempsey Center was “very helpful” in her family’s encounter with cancer. She was especially appreciative of a memorial ceremony the Dempsey Center arranged last year.

Other teams included Caroline’s Commandos, Wombat’s Warriors, Team Angela and Team Aubrey.

The bright-pink wigs and pink tutus worn by the “Real Housewives of North Monmouth” were easy to spot in the river of runners and walkers. Laurie Gile said the group, all neighbors, were taking part in the Dempsey Challenge for a fifth year.

In remarks to the walkers and runners from the start stage, Dempsey told participants, “We’ve hit a million dollars again, which is amazing.” He asked for a show of hands by people who had participated in previous years’ Dempsey Center events, and a majority of people in the crowd responded.

Lunden told the crowd her battle with cancer taught her that the “unsung heroes” in the eyes of cancer patients are the nurses and volunteers who help them in their journey.

Lunden was participating in the Dempsey Challenge as the Amgen Breakaway from Cancer Honorary Champion. She is a special correspondent for NBC’s “Today” show. She was co-host of ABC’s “Good Morning America” from 1980 to 1997, has written eight books and is a motivational speaker.

Fundraising tallies Saturday morning included $25,000 raised by top individual fundraiser David Gervais of Lewiston. He said he accomplished the hefty amount with a door-to-door effort, as well as many letters and contacts with “more people, and more people and more people.”

Katy Romano of Atlanta, Ga., a major fundraiser in previous years as well, was recognized for $24,000 in donations. Butler Brothers of Lewiston contributed $48,000 in team fundraising.

Dempsey sent each group on its way from the stage at the Oxford Street starting point, waving constantly as hundreds of participants passed. He was frequently moving off stage, where he posed for photos with just about everyone who approached. Lunden was also a gracious ambassador for Amgen, a multinational biopharmaceutical company headquartered in Thousand Oaks, Calif., that is the Dempsey Challenge’s leading sponsor.

When asked where they had traveled from, people in the crowd shouted out Florida, Ohio, Michigan, New York, Canada, Venezuela, Italy, Germany, United Kingdom, Egypt and Africa.

The Dempsey Challenge will continue at Simard-Payne Memorial Park on Sunday, beginning with the start of the biking portion of the event. Cyclists will start at 7:30 a.m., choosing trips of 100, 75, 50, 25 or 10 miles. The family-friendly Festival in the Park, which goes on all day in conjunction with the Challenge, includes a KidZone, band music on the central stage, tents offering health information and several food vendors.