Six-time Olympic gold medallist Sir Chris Hoy said on Friday that he has been diagnosed with cancer.
The former team GB track cyclist, 47, revealed his diagnosis in a post on Instagram, saying that he had hoped to have kept the matter private, but that his "hand has been forced."
Hoy became Britain's most decorated Olympian when he won the sixth gold medal of his career at the 2012 Olympics in London, surpassing the previous record of five set by rower Sir Steve Redgrave.
His total has since been beaten by fellow track cyclist Sir Jason Kenny who won his seventh gold medal in Tokyo. Kenny has also won two silvers.
"I have a bit of news. Last year I was diagnosed with cancer, which came as a huge shock, having had no symptoms up to that point," Hoy said.
"I'm currently receiving treatment including chemotherapy, which thankfully is going really well. I'd like to extend my sincere gratitude to all the medical professionals for their amazing help and care.
"For the sake of my young family, I had hoped to keep this information private but regrettably our hand has been forced. Whilst I'm thankful for any support, I'd like to deal with this privately.
"My heart goes out to the many others who are also going through similar challenges right now."
Hoy was at the vanguard of Britain's era of domination in track cycling as the sprint specialist claimed 11 world titles during a glittering career.
The Scot was knighted after winning three gold medals at the 2008 Olympics in Beijing.
"I'm optimistic, positive and surrounded by love for which I'm truly grateful. As you might imagine, the last few months have been incredibly difficult," Hoy added.
"However, I currently feel fine -- I am continuing to work, ride my bike and live my life as normal.
"It's an exciting year of work ahead, not least with the Paris Olympics in July. I can't wait to get stuck in, have fun and share it with you all."
Information from Reuters contributed to this report