Anastacia's career is a testament to tenacity. A former Club MTV dancer and backup singer for the likes of Tiffany, she signed to a major label just before she turned 30 and has dealt with serious health problems, including breast cancer and tachycardia, while recording and touring the world. Her forward-thinking, omnivorous idea of what pop could be, as well as her powerful, distinctive mezzo-soprano, helped make her an international superstar, one capable of holding her own alongside big voices like Luciano Pavarotti and Celine Dion.