David Brooks is confident he will make a full recovery and return to playing after the Bournemouth and Wales midfielder was diagnosed with cancer.
Brooks was with the Wales squad last week for their World Cup qualifiers but left international duty and underwent a medical examination, which found he has stage two Hodgkin lymphoma.
The 24-year-old will undergo treatment next week.
"This is a very difficult message for me to write," Brooks said in a statement.
"I have been diagnosed with stage two Hodgkin lymphoma and will begin a course of treatment next week.
"Although this has come as a shock to myself and my family, the prognosis is a positive one and I am confident that I will make a full recovery and be back playing as soon as possible...
"I want to thank everyone at the Football Association of Wales because without the swift attention of their medical team we may not have detected the illness.
"I'd also like to say thank you to AFC Bournemouth for all their support and assistance this past week... thank you to everyone for their messages of support - it means so much and will continue to do so in the months ahead.
"I look forward to seeing you all again and playing the sport I love very soon."
Bournemouth chief executive Neill Blake said that the Championship club would not put a time frame on his return.
"We'll give David all the time he needs to get well and will do everything that we possibly can to help with that," he said.
Brooks joined Bournemouth from Sheffield United in 2018 and enjoyed an impressive first season with the club, scoring seven goals and assisting five in 33 games in all competitions.
Injuries limited Brooks the following year as Bournemouth were relegated, but he impressed again in the Championship, this time with 13 goal involvements across all competitions.
This term, he has three goals in nine matches.