Leah Still is facing a "pretty serious complication" in her fight against cancer, her father, NFL player Devon Still, announced via Instagram on Friday night.
"I need some prayers sent up for Leah tonight!" the defensive tackle for the Cincinnati Bengals wrote in the post's caption. "We hit a pretty serious complication from the stem cell transplant called VOD. They caught it early so hopefully it gives doctors a better chance of stopping it from getting aggressive."
Still added: "As you can imagine our minds are all over the place but we're going to try and remain positive!"
"VOD" is an acronym for veno-occlusive disease, which according to the National Cancer Institute is a complication of high-dose chemotherapy given before a stem cell transplant marked by small veins in the liver being obstructed.
Continuing his message of #LeahStrong, Still shared on Instagram Monday, a tattoo of Leah's face he got on his back.
"In a couple of days it's going to be a year since my daughter was diagnosed with cancer so I decided to dedicate a back piece to her," Still wrote in the post's caption.
In March, Leah's father, a defensive lineman with the Cincinnati Bengals, announced via Instagram that she appeared to be cancer free, though at the time, she still needed to undergo stem cell treatments.
Leah, who turned 5 earlier this month, was first diagnosed with Stage IV neuroblastoma in June 2014. At the time, doctors estimated her chance of survival was 50-50.
Since her initial diagnosis almost a year ago, Leah's fight against pediatric cancer has inspired many across the country. In November, the Bengals presented a $1.3 million check to the Cincinnati Children's Hospital that was raised through the sale of Still's No. 75 jersey.
Leah has since strutted her stuff during New York's Fashion Week, joined her father on a children's book, "I Am Leah Strong," and appeared in TODAY's Hoda Kotb's "Truly Brave" video.
Kotb, who has been one of Leah's biggest fans throughout her battle against cancer, visited Leah in the hospital on Friday, sharing a photo of the visit on social media with the caption, "Sweet Leah."