David Yamada cannot understand why anyone capable of donating bone marrow to save a life would refuse to do it.

“;Can you imagine having a match and the person backs out?”; he asks. “;The family must be devastated.”;

Roy Yonashiro, donor recruitment coordinator at the Hawaii Bone Marrow Registry, confirms such heart-dropping disappointment.

“;The worst thing for us is when we call the donors that they're a match, and they tell us no,”; said Yonashiro. “;About 50 percent of the people we call turn us down. They say, 'I changed my mind. I wasn't thinking right. Everybody was doing it (signing up) and I thought I'd do it. I didn't think I'd ever be called.'”;

Yet those who follow through say the rewards are immense.

For Yamada, 49, it comes in the form of a drawing every Christmas from a girl in Sacramento, Calif.

He donated twice in 2002—first bone marrow and then stem cells—to save the life of Erica Tsuchihashi, then 18 months and battling leukemia. She is now almost 9 and “;doing very well,”; Yamada said.

He met the child and her parents, Hiromi and Tetsuro, in 2005 at a celebration for the registry at the Sheraton Waikiki.

“;It was really strange to look at someone and say, 'Oh, my gosh, with what little I did, this person is alive and well,'”; he said. “;The parents got to enjoy their child. ... To this day, that's what keeps driving me on to help people as often as I can.”;

Yamada said he signed up as a bone marrow donor in about 1996 at a Japanese festival in San Francisco.

“;I had been giving blood since I was a kid,”; he recalls. “;It seemed a natural progression. They said they needed Asian donors.”;

He had gone to California to care for his father, who died of bone marrow cancer in 2001, he said.

“;It seemed that I was destined to do this.”;

Now he helps with bone marrow drives as an “;ambassador”; for the registry to help people understand what being a donor involves. “;It's really important to have someone there with experience,”; he said.

Dale Nishikawa, 56, also a two-time donor and volunteer for the registry, said he first gave bone marrow and then “;specialized blood cells”; to one patient.

He received a letter through the national registry from the recipient, “;telling me he was doing good and was happy and thankful.”;

Like Yamada, Nishikawa continues to help the registry, sharing his experience with potential donors.

“;Bone marrow and blood cells—you can give it away and it'll come back,”; he said. “;It's not like making a huge sacrifice.”;

A former trombone player with Glass Candle, Nishikawa is a guest artist at the registry's Friday fundraiser.

The Hawaii Registry has since 1989 successfully matched nearly 300 patients and developed a list of more than 70,000 potential donors.

The registration process simply involves a swab of cells inside a donor's mouth. The sample is sent to the national repository for testing and storage.

Pacific Island donors are the biggest need, Yonashiro said.