THE HAGUE, Netherlands (AP) — Esther Vergeer, the retired Dutch wheelchair tennis star who had a winning streak of 470 matches during her record-breaking career, has been diagnosed with breast cancer.

Vergeer announced the diagnosis in a tweet Wednesday, saying her “full focus will be on the treatment and healing of the cancer. Full of positive energy and with the support of my family, friends and colleagues, I will go for it. I am sure I will get through this!”

The 38-year-old Vergeer has used a wheelchair since she was 8, when an operation to correct hemorrhaging around her spinal cord left her paraplegic.

She took up wheelchair tennis and strung together a list of titles that led Richard Krajicek, the 1996 Wimbledon champion, to call her “perhaps the most successful sportsperson of all time.”

Her winning streak lasted from 2003-2012. During that time she won 25 Grand Slam titles, four Paralympic singles gold medals and three doubles golds.

Vergeer is the leader of the Dutch team for the Tokyo Paralympics Games, which open on Aug. 25.