"Grey's Anatomy" star Patrick Dempsey joined thousands of other participants last weekend in Maine as part of the 6th annual "Dempsey Challenge" charity race. The two-day event, the main fundraiser for the Patrick Dempsey Center for Cancer Hope and Healing, is a celebration of health, wellness, walking, running and biking. 

This year's race was particularly emotional for Dempsey and his family, as it comes only months after his mother, Amanda Dempsey, lost her own battle with ovarian cancer. The 79-year-old was the inspiration behind both the cancer center and the race, inspiring so many with her courage and generosity. 

"For a family to get a cancer diagnosis is devastating, and all the information out there can be overwhelming," Dempsey said in 2011. "A lot of the websites I went to just didn't have enough information. So I talked to my sister about a place where people could go for all this type of information and help. Knowledge is power."

The center, which provides free cancer support, education, and integrative medicine services to anyone impacted by cancer, has become an integral part of the Central Maine Medical Center in Lewiston. Last year alone, more than 16,000 people were helped either in person or via phone through the center's outreach program. Thanks to the generosity of all those who participate in the Dempsey Challenge, it's a vital resource that will continue to benefit many more in the future. 

Check out a video "thank you" message to this year's participants and donors from Patrick Dempsey below.