NASHUA — Hundreds gathered Sunday night at the Church of Jesus Christ of the Latter Day Saints for a memorial service for Hillary Alexandra Hansen.

Alex was born Oct. 24, 1999, to Curtis and Michelle Hansen of Milford, a couple who said they wanted nothing more than to have a child to call their own.

“That morning, I held the most beautiful girl in the world in my arms,” Michelle told the mourners Sunday. “But there was something different about this little girl, something unique about my sweet little Alex.”

At 31/2, the Hansens were at a picnic with friends when they noticed their daughter limping. A few days later, they took her to the pediatrician who took one look at the child and immediately sent the family to Children’s Hospital in Boston, Curtis Hansen said.

“She said, ‘I want you to get in your car and drive to Children’s Hospital. Don’t go home and pack a bag, just go.’”

When they arrived, doctors performed a CAT scan and found a tumor the size of a tangerine on her brain. The next day, the tumor had grown to the size of a grapefruit. The doctors at Children’s Hospital operated, and against all odds, saved Alex’s life. The Hansens said she thrived and welcomed three sisters into the world, and studied her heart out at Jacques Memorial and Heron Pond schools in Milford. But last year, the cancer returned.

In May, the family received word the cancer had become untreatable, and there were no options left. So the family piled into a rented RV and drove toward Utah so that Alex could have her wish of seeing her cousins and her grandparents one last time. She died shortly after getting her wish, surrounded by her family.

“Alex is not just my sister, she’s my best friend,” her sister Jenna said Sunday night. “I miss her laugh.”

Jenna said Alex was excited about being 12 and was looking forward to Dec. 12, 2012, because she would be 12 on 12/12/12. But instead, she settled for 6/12/12.

“That was Alex’s special day because she returned to heaven,” Jenna said.

Michelle spoke of a morning this spring when the family went to Parker’s Maple Barn in Mason, Alex’s favorite restaurant. As she ate her favorite meal — a Belgian waffle with syrup made right on site — she looked around the room, “taking in everything in a complete state of happiness.”

“She enjoyed everything so many of us take for granted every day,” Michelle Hansen said.

Despite the difficulties caused by her cancer, she kept attending school when she had to rely on a walker, and then, a wheelchair.

“Twelve years was not long enough for me, but it was long enough for her,” said Michelle. “The hardest thing was saying goodbye to her, that it was OK to let go.”

Alex’s father said the question he has been asked most often was how God could allow a child like Alex to suffer. But Curtis Hansen said he believed that before Alex was born, she raised her hand and volunteered to spend those 12 years on earth to teach her parents, her sisters, and everyone she met how to withstand the challenges of life and to learn the lessons in suffering.

“I wish that she was still here, but I’m so glad she’s not in pain anymore,” he said. “I know that she lives on, and I know that we will have the opportunity to be a family again, and to listen to her tell her corny jokes with the punch line in the wrong place. I cannot wait for that day.”

nfoster@newstote.com