The tennis legend was diagnosed with a non-invasive form of breast cancer in 2010, from which she made a full recovery.
Tennis legend Martina Navratilova has revealed she has been diagnosed with throat and breast cancer.
In a statement released by her representative, the 18-time Grand Slam singles champion and member of the International Tennis Hall of Fame said she will start treatment later this month.
"This double whammy is serious but still fixable, and I'm hoping for a favorable outcome," the 66-year-old said in the statement, via the WTA website. "It's going to stink for a while but I'll fight with all have I got.''
The multiple major winner in doubles, who won the calendar slam in that form with Pam Shriver in 1984, said she noticed an enlarged lymph node in her neck while attending the season-ending WTA Finals in Fort Worth, Texas, in November. A biopsy later revealed early stage throat cancer. While Navratilova was undergoing tests for the stage 1 throat cancer, she said, the unrelated breast cancer was discovered.
Specifically, the throat cancer is human papillomavirus (HPV), one of the more treatable cancers, according to the statement.
Navratilova was diagnosed with a noninvasive form of breast cancer in 2010 and had a lumpectomy, from which she made a full recovery.
A few hours after the announcement, Navratilova took to Twitter and said: "Needless to say my phone and Twitter are both blowing up so I will say again. Thank you all for your support and I am not done yet."
The Czech-born tennis player won 59 Grand Slam titles overall, including 31 in women's doubles and 10 in mixed doubles. The last major title was a mixed doubles championship with Bob Bryan at the 2006 U.S. Open, a month before her 50th birthday.
She originally retired in 1994, after a record 167 singles titles and 331 weeks at No. 1 in the world rankings. She came back to play doubles in 2000 and occasionally competed in singles, too.
In 2000, Navratilova was inducted into the International Tennis Hall of Fame.
She has worked as a TV analyst in recent years, most notably as part of the team at the Tennis Channel.
Monday's statement said Navratilova would not be a regular part of Tennis Channel's coverage of the Australian Open, due to get underway on 17 January "but hopes to be able to join in from time to time" via video conference.