The news "really hit me hard," says Tavarez.
Her struggle also struck a chord with Alicia Keys and Rihanna. The singers, who both started their careers when they were young, decided to help get the word out that Tavarez needs a bone marrow transplant to live.
Keys hopes Tavarez and other patients like her to have the chance to "grow up to live their dreams."
Rihanna seconds that sentiment. "[Tavarez] should be performing on Broadway, but is confined to her bed, fighting for her life," Rihanna tells PEOPLE. "She needs to find a bone marrow donor to survive. I urge all my fans to register [as donors]. It's the most beautiful thing someone could do, to give the gift of life."