The tennis Hall of Famer announced the news Monday on Twitter after what she said was a full day of tests at Memorial Sloan Kettering Cancer Center.

“Thank you to all the doctors, nurses, proton and radiation magicians etc- what a relief,” she wrote.

Navratilova, 66, revealed that she had been diagnosed with throat cancer and breast cancer in January and that she would begin treatment that month. She had been diagnosed with a non-invasive form of breast cancer in 2010 and had a lumpectomy.

The 18-time Grand Slam singles champion had noticed an enlarged lymph node in her neck in November, and a biopsy revealed the early stage throat cancer. But Navratilova felt well enough to return to her TV work with the Tennis Channel by the Miami Open in March.