"But I started noticing she was very tired and fatigued and it wasn't normal," said Brown, 38. "She'd never been like that before. She looked peaked and that wasn't normal for her."
Shannon had trouble getting out of bed to go to school and later told her mother that keeping up with the "Lion King" was tough, too.
"She confessed to me that her legs and lower back were hurting while she was on stage and had to run up the stairs on the show," said Brown. "Then someone on the show said, 'Shannon needs rest, she seems tired."
Blood tests revealed that Shannon had acute myelogenous (AML) leukemia, a cancer of the bone marrow and blood.
"The day we found out, we immediately admitted our lives had just changed completely," said Brown. "We go into the city every day now and we are actually practically living at the hospital."
Leukemia is a rapidly-progressing disease that results in the accumulation of immature, functionless cells in the marrow and blood, according to the Leukemia and Lymphoma Society. In many cases the bone marrow stops producing enough normal red cells, white cells and platelets. Anemia, a deficiency of red cells, develops in virtually all persons with leukemia.
Some 245,225 Americans are living with leukemia and an estimated 44,790 new cases are diagnosed in adults each year. Another 3,509 children up to the age of 14 get the disease each year.
Shannon's type of cancer is one of the least common of childhood leukemias, though it is the most common form in adults, according to Dr. Barbara Asselin, assistant professor of pediatrics and oncology at Golisano Children's Hospital at the University of Rochester Medical Center.
"It is generally an aggressive disease that requires chemotherapy," she said. "The first hurdle is to see if we can achieve a remission in the bone marrow and don't see any more leukemia cells, which know can hide in the body. A good response to early therapy is a factor in a good prognosis."
A bone marrow transplant can also be part of the first line of therapy, she said, but doesn't mean an "absolute cure."
"The chances of getting into remission are less and an eventual cure is less [than other types of childhood leukemia], but I am always optimistic about a cure," said Asselin.
Shannon was hospitalized for two months, undergoing chemotherapy. She temporarily lost her hair but suffered no other side effects like nausea or loss of appetite. She gave her family a scare when she developed an IV line infection, but it later resolved.
Today, Shannon is back home, watching movies -- she loves "Mean Girls" -- connecting with friends on Facebook and making string bracelets.
"I am just thinking positive that I get through this," said Shannon, who has been promised she can return to her Broadway role when she recovers. "I am excited for when everything will go back to normal."
Her mother is hopeful that Shannon will be able to make it to fifth grade next January, if a bone marrow transplant is successful.
"She's an energetic, very intelligent and very articulate girl, full of life," said Brown. "She is always excited, always asking questions and has this infectious spirit and knows how to pull people in. They all fall in love with her. I know -- I am her mother -- but that's the thing with her."
But Brown said she has her days when she has trouble coping with the thought of losing her daughter.