Teen Invites Cancer-Stricken Sister to His First High School Dance

— -- A South Dakota teen made the experience of going to his first high school formal a family affair by inviting his younger sister, who is battling cancer.

AJ Spader, 15, told his parents of his plan to invite his sister Rebekah, 10, as a way to make meaningful memories.

"He came to us and said, 'Rebekah might not get to go to her own dance,'" AJ's mother, Stephanie Spader, told ABC News today. "He wanted to give her that experience."

AJ was determined to make the event special for Rebekah, Spader said, and even used the family motto of "Unbroken, brave and blessed" on a big poster to ask her to the dance.

“She's most likely not going to be able to experience high school. So, I just thought why not ask her to the formal,” AJ told ABC affiliate KSFY.

Rebekah was diagnosed with myelodysplastic syndrome four years ago and multiple treatments, including a bone marrow transplant, have failed, Spader said.

"I want to spend as much time with her as possible while she's still doing good," AJ told KSFY.

For the Valentine's Day formal, Rebekah got to enjoy a full day of pampering, Spader said. "Her 12-year-old sister did her make-up and her grandma did her hair, so it was a family affair."

Rebekah posed for pictures in her formal dress and tiara alongside her brother and his friends before going to dinner together.

"Rebeka and AJ have a close relationship and he has a really big heart," Spader said. He wanted to "allow her to do something that she wouldn’t get to do."

Though Rebekah didn't end up actually arriving at the dance because she got too nervous, Spader said it was a special night.

"AJ and his friends embraced her and embraced the situation and didn’t blink twice that a little 10-year-old sister was going to hang out with them," Spader said. "That for me was the most special thing."