After a routine blood test, Kayla DeFeo was diagnosed at age 2 with leukemia. Her mother, Debby Formica, remembers sitting down and trying to explain what was happening to Shannon, Kayla’s twin, and Jessica, her 3-year-old sister. She could hardly understand it herself.

“I was kind of confused,” says Jessica, now 12. “And I kind of still am. We’re just now starting to understand it, which is a weird feeling. It’s kind of like relief.” Her sister Shannon, now 11, agrees.

When cancer strikes a 2-year-old, it’s a bolt out of the blue. While more the 3 in 4 cases of pediatric cancer can be cured, unfortunately, Kayla’s was not. She died in 2011, five years after her diagnosis.

Her family is left with wonderful memories. “Kayla had the most infectious laugh you will ever hear,” recalls her mother. Jessica remembers Kayla trying to repeat the Peter Piper pickled pepper tongue twister, and just dissolving into giggles. Shannon remembers how her sister would eat absolutely any food. “We used to call her the trash can,” adds Debby.

This year, Jessica and Shannon are sibling ambassadors for the Four Seasons Parkway Run & Walk, which will take place on Sept. 19 at Lincoln Financial Field. It is the family’s 10th Parkway Run.

“The day of the Parkway Run is sort of like a holiday to my family,” says Shannon. “We all get together and we’re with our friends and family and we all have the drive to do something and to help people. I just really love that.”

“Once you go through this,” adds her mom, “you just understand what’s important. There’s so many things in life that you just shouldn’t sweat. Things like having a sick child, being involved in a cause that you believe in, having your family and friends all around you — that’s what’s important. That’s all that matters in life.”