Cancer survivor Rees reveals 'dark days'
Wales' hooker Mattew Rees is pictured on February 24, 2007, at the Stade de France in Saint-Denis, north of Paris - by Damien Meyer
Rees was diagnosed with the illness in October but, following treatment, he returned to action in Cardiff Blues' 28-23 Celtic League win over Ulster on Saturday.
The 33-year-old British and Irish Lions hooker marked his playing comeback as a second-half replacement at the Cardiff Arms Park.
"I think the most important thing in life is your health. If you haven't got your health, you haven't got anything," Rees told the walesonline website.
"Obviously there were some days where I thought I would never play the game again and some days where I thought I can get back on the field.
"It was just a case of being positive all the way and speaking to the nurses on a regular basis about the success rate, where I was going.
"I had some dark days, but it's a challenge and I have overcome that and obviously come out the other side, and it's just good to be back involved in the rugby side of it.
"I'm glad to say I have come out the other side and am obviously back on the field. An experience like that in your life will change you."
Rees added he'd been able to resume preliminary training while still undergoing treatment.
"It was unknown territory to know how I was going to react, but I was lucky enough to keep on in pretty good shape.
"I had a six-week block which I targeted as a mini pre-season to get back in time for the tail end of the season and hopefully play the last couple of games."