The 2010  Shave for the Brave event hosted by the advocacy group 46 Mommas. (Photo courtesy of 46 Mommas)

When 10-year-old David Heard succumbed to cancer this winter after a two-year fight, he wrote a list of things he wanted his mother, Susan, to complete for him after he was gone. This evening, as his mother sits  in a barber’s chair on a podium in Washington’s  Union Square, she’ll  strike from the list one of David’s items: Shave your head for cancer awareness.

“By shaving my head, I’m really fulfilling a promise I made to him,” Heard told ABCnews.com.

Susan Heard, along with 45 other mothers of children with cancer, will shed their locks as part of   Shave for the Brave  – an event run by 46 Mommas, an advocacy group for childhood cancer, and St. Baldrick’s Conquer Kids Cancer.

The group 46 Mommas, which  takes its name from the fact that each weekday an average of 46 mothers across the U.S. will hear the diagnosis: “Your child has cancer,” meets  in D.C this week to  bring awareness to childhood cancer and to offer support to the 2nd Annual Childhood Cancer Summit.  The women are also in Washington on behalf of the  Creating Hope Act, which they will present  to the Congressional Pediatric Cancer Caucus on Friday.  The act would create incentives for pharmaceutical companies to develop childhood cancer treatments.

“The biggest obstacle with treating childhood cancer is   there’s so many different types of cancer that the pool of patients is so small for each. It’s hard to do research when there are so few kids out there to test new therapies on, and the research interest is low because pharmaceutical companies are really not interested in investing in a drug that can’t be mass marketed,” says Heard.

Only 650 children are diagnosed each year with neuroblastoma, the cancer Heard’s  son David had.  Even though  each type of cancer may have a relatively small pool when compared with some adult cancers, the overall number of children with cancer is much higher.