The organisation was founded by Jenny Stanger in 2012 as Haywards Heath Prostate Cancer Support Group and rebranded in 2020 to serve a wider area.
Vice chairman Rob Stanley, 71, from Mannings Heath, said the celebration is planned for June 17 at Clayton Village Hall (2pm-5pm).
He said: "Normally when we have a face-to-face meeting we have presentations and all kinds of stuff, but this, being our tenth anniversary, is just going to be a pure social occasion."
Rob said the group, which now has more than 80 members, aims to support men with prostate cancer at ‘the earliest possible point’ after diagnosis.
He said: "When you're diagnosed with prostate cancer you are bombarded with information and options.
"Some of the options are bewildering and it's really important that a guy makes the right sort of decision about his future."
Rob said he was diagnosed with prostate cancer six years ago and that other members were diagnosed ten years ago, meaning they have a wealth of knowledge to share.
He said the group cannot offer medical advice but encourages men to open up and share their experiences.
There is a Zoom chat on Friday afternoons and every two months there is a face-to-face meeting at Haywards Heath Social Club. Rob organises a walk every fortnight.
The group also runs free prostate specific antigen (PSA) testing days.
Rob said he joined the group a year and a half ago after meeting the chairman at a radiotherapy session.
He had his prostate removed six years ago but the cancer came back in 2019, leaving him ‘at a real low’ and unwilling to meet others.
But Rob said he received 'an amazing amount of support' from the group.
He said: “The most important thing was to realise that there are thousands and thousands of guys all going through the same thing."