'Raindrops Keep Fallin' On My Head' singer B.J. Thomas has been diagnosed with stage four lung cancer.

The Grammy-winner's representative has issued a statement on the singer's behalf, in which he shared his "gratitude" for his wife Gloria, his "rock for over 53 years", and his fans.

It read: “I just wanted to take this unique opportunity to share my gratitude to Gloria, my wonderful wife and my rock for over 53 years, my family, friends, and fans.

“I’m so blessed to have had the opportunity to record and perform beautiful songs in pop, country, and gospel music, and to share those wonderful songs and memories around the world with millions of you. I ask all of you for your prayers during this time and that my music can live on with you.”

Deadline reports that the 78-year-old star is undergoing treatment at a facility in Texas.

Born in Oklahoma, B.J. had a breakthrough in his music career in 1966, when his cover of Hank Williams' 1949 track 'I'm So Lonesome I Could Cry' became a top 10 hit on the Billboard Hot 100. He'd follow that up with 1968's 'Hooked on a Feeling'.

A year later, his cover of Burt Bacharach and Hal David's 'Raindrops Keep Fallin' On My Head' soundtracked 'Butch Cassidy and the Sundance Kid' and won the Oscar for Best Song,

It also marked his first number one and spent four weeks at the top of the chart in 1970.

B.J. earned his first-ever Grammy nod for the hit, and though he didn't win on that occasion, the singer went on to nab a Grammy every year between 1976 to 1981 for the likes of 'The Lord’s Prayer', 'Amazing Grace' and his 1976 album 'Home Where I Belong'.

B.J.'s singing voice can be heard in classic movies and TV shows such as 'Forrest Gump', 'Spider-Man 2' to 'Family Guy', and as recent as 2020's 'Mrs. America'.