But, thanks to treatment, plus his determination not to let cancer change him, he is now back coaching and playing at international level.
And this Wednesday (1st August 2018) he is running a fundraising tennis festival in Brighton, with some amazing sporting prizes.
The event, called British Tennis Battles The Big C
, at Preston Lawn Tennis Club
on Preston Drove, includes a Davis Cup-style doubles fest, featuring Davis Cup stars, a Wimbledon champion and a host of former and current British tennis pros.
Auction prizes include ATP men"s world tour tickets, a chance to play at Wimbledon with Barry Cowan, a round of golf with Billy McManus and directors box experience at Old Trafford.
Barry, 38, who lives in Prestonville, Brighton, is captain of the Great Britain under-35 squad and last year was ranked second in the world in that age group.
"After I was diagnosed, there were dark and challenging days, watching my body disintegrate as the cocktail of chemotherapy, anti-sickness drugs and steroids kicked in.
"I had only been married four weeks and my life was plunged into turmoil. A precautionary check-up led to me having an urgent, radical orchidectomy – removal of the testicle.
"The surgery coincided with my 28th birthday. There was worse news too – the cancer had already spread."
In the middle of treatment, Barry also had to give the best man's speech at his brother's wedding, and there wasn't a dry eye in the house.
Barry's brother said:"I and many others in the room broke down in tears at the sight of this skinny, depleted, balding, fatigued version of Barry trying to deliver a speech."
However, with the support of his wife Suzie, and other family and friends, he got through the treatment and fought his way back to recovery.
"Since then, I've been blessed with two beautiful daughters - Isla and Marnie, who are now eight and four respectively. They have joined Callum, 21, and Louis, 18, in our family.
"Like many, I have had a few scares over the past ten years, most recently last year, which can bring all sorts of emotions flooding back.
"But I consider myself a cancer survivor - one of the fortunate ones who fought and overcame The Big C!
"I never wanted cancer to shape me but equally, I never want to forget the perspective it brought and the lessons it taught me."
Barry said the tennis festival was a guaranteed day of fun and entertainment.
"Whether you play the sport, enjoy watching it or just want to contribute to a great cause. We"ll have some of Britain"s top talent on display, so please come down and enjoy."
For more info on how to donate, visit: