Islanders Hockey Fights Cancer Stories of Strength: Siobhan O’Sullivan

Each month, the New York Islanders and Northwell Health are spotlighting two strong and inspiring children battling cancer in continuous support of pediatric cancer patients all season long.

Siobhan O’Sullivan's early years were nothing out of the ordinary. She did well in school, played soccer, volleyball and basketball and was overall a social butterfly.

“She was a regular, normal and happy kid,” Siobhan’s mother, Maura O’Sullivan, said.

Everything changed on May 7, 2018, for the O’Sullivan family, as they found out Siobhan was diagnosed with Acute Lymphoblastic Leukemia (ALL).

Siobhan was taken to Cohen Children’s Medical Center to be treated, and on the first night she read an inspirational sign in the hospital. It read, “You’re braver than you believe, stronger than you seem and smarter than you think.” This was Siobhan’s new motto to live by going forward.

Cohen’s medical staff as she finished treatment in July of 2021 and the O’Sullivan’s are forever grateful. Siobhan’s fight was only strengthened by a massive rally among her hometown community in Rockaway Beach, Queens.

“It’s a very close-knit community,” Maura said. “Between neighbors, our church and our friends. They rallied around her endlessly.”

Her softball team even began the “Siobhan Strong” movement, all of them wearing socks with that message during games while she was in treatment.

Sports were a place of strength, and Cohen’s connected her with professional teams in New York. One of them was the Islanders, who extended several opportunities that made her smile, while simultaneously spreading greater cancer awareness.

In 2019, Islanders forward Josh Bailey donated two game tickets to Siobhan, which included a meet and greet afterwards. She also took part in a virtual puck drop for the Islanders’ Hockey Fights Cancer initiative during the COVID pandemic. Casey Cizikas, Scott Mayfield and Matt Martin all took the time to visit her at the hospital during the holiday season, bringing her joy during a tough time.

“The Islanders were so wonderful to her,” Maura said.

Siobhan decided to take part in the Islanders’ 2025 HFC night again. She met more players, including Anders Lee, received HFC specific gear and experienced the game from the DIME Club at UBS Arena. She helped the team escalate cancer awareness through her first-hand experience.

“It’s incredible,” Maura said. “I love that every team does it ... to share how important it is that we never forget that cancer is affecting everyone.”

Siobhan didn’t just want to watch sports. Getting back to competing was her goal. Once she was medically cleared, and her family engineered a port protector, which allowed her to play soccer, even while going through treatment. Nothing ever got in the way of Siobhan.

“She never felt bad for herself,” Maura said. “She would push herself real hard ... [and] I think that has made her who she is today.”

Siobhan completed treatment on July 16, 2021, making a tremendous impact en route to returning to her day-to-day life. She and another cancer survivor raised around $200,000 for the Leukemia Lymphoma Society (LLS), and Siobhan, now a sophomore, made the varsity rosters in basketball and volleyball.

Once she graduates from high school, Siobhan wants to return the support and go to school and study to become a speech therapist.