The 24-year-old was named in the Wales squad for World Cup qualifiers against Czech Republic and Estonia during the recent international break but was forced to withdraw due to illness.
Brooks has now provided some clarity on what necessitated his withdrawal with a lengthy post on social media.
"This is a very difficult message for me to write,” the former Manchester City academy star said.
"I have been diagnosed with Stage II 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'd like to show my appreciation to the doctors, nurses, consultants and staff who have been treating me for their professionalism, warmth and understanding during this period.
"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 of their support and assistance this past week.
"Although I appreciate that there will be media attention and interest, I would like to ask that my privacy is respected in the coming months and I will share updates on my progress when I am able to do so.
"In the meantime, 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."
Brooks was part of the Wales squad at EURO 2020 and has featured seven times in the Championship for Bournemouth this season.
