Rock singer Kaori Kawamura, who had spoken openly about her battle with cancer, died Tuesday at a Tokyo hospital, her management office said. She was 38.

Kawamura, also known as an activist on breast cancer, started her professional career in 1988 at age 17 with the single "ZOO."

She was diagnosed with breast cancer in 2004 and underwent surgery.

Kawamura wrote last year on her blog that the cancer had spread to her lungs, lymph nodes and bones.