Megadeth have cancelled most of their upcoming tour as frontman Dave Mustaine undergoes treatment for throat cancer.
Mustaine announced his diagnosis on the metal band's website, but said he was optimistic about his treatment plan.
"It's clearly something to be respected and faced head on - but I've faced obstacles before," he said.
"I'm working closely with my doctors, and we've mapped out a treatment plan which they feel has a 90% success rate. Treatment has already begun."
Although the majority of Megadeth's tour dates have been cancelled, the recently-announced "Megacruise" will take place as scheduled in October "and the band will be a part of it in some form", Mustaine wrote.
Billed as "five days and nights of heavy metal decadence and debauchery," the cruise is due to feature concerts, masterclasses and meet-and-greets with the band.
Mustaine added that the group would continue to work on the follow-up to their Grammy-winning 2016 album Dystopia while he receives treatment.
"I'm so thankful for my whole team - family, doctors, band members, trainers, and more," he said. "I'll keep everyone posted."
Fans and fellow artists were quick to send messages wishing Mustaine the best.
Anthrax's Scott Ian said: "Please join me in sending all of our most powerful positive mind bullets to my brother Dave. You got this my friend, you can beat it - like you beat me in arm-wrestling! Kick its ass and get healthy!"
"Prayers and positive vibes out to my friend. Cancer doesn't stand a chance fighting this guy!" added Mike Portnoy of Dream Theater and Sons of Apollo.
"Tout le monde is with you, Dave," said Lacuna Coil frontwoman Cristina Scabbia. "We all love you and are with you."
Mustaine's Megadeth bandmate David Ellefson wrote: "Praying for my friend Dave Mustaine for a full and speedy recovery!"
The star's daughter, Electra, added: "I would do and give anything for this man. Dad, I love you so so much. You've taught me what love should look like, taught me reliability, perseverance, commitment... and mostly, strength.
"On days when you can't, I will give you mine."
Mustaine formed Megadeth in 1983 after an acrimonious split with Metallica, where he was the original lead guitarist.
The band were pioneers of what came to be known as "thrash metal", playing faster and louder than their contemporaries, with an emphasis on Mustaine's lightning-fast guitar skills.
Their independently-released debut Killing Is My Business... And Business Is Good! won them a major recording contract with Capitol Records, who released the platinum-selling Peace Sells... But Who's Buying? in 1986.
The band's early success was marred by Mustaine's drug addiction, culminating in an arrest for driving under the influence in 1990.
After entering a rehabilitation programme and getting clean, Mustaine refocused his attention on the band, culminating in the release of 1992's Countdown to Extinction - the band's most commercially-successful album, and a sign that metal still had an audience in the midst of grunge.
The album's title track also won an award from the Humane Society in 1993 for raising awareness for animal rights issues.
However, the band nearly came to an end in 2002, when Mustaine fell asleep with his arm over the back of a chair - causing severe radial nerve damage.
Doctors told him he might regain 80% of his movement back - but he'd never play guitar again. Undeterred, the star went through 18 months of painful therapy and got himself back on stage by 2004.
Their last album, Dystopia, was released in 2016, and the title track earned the band their first-ever Grammy, for best metal performance.
Earlier this year, Megadeth released the career retrospective Warheads on Foreheads, and were set to celebrate the 35th anniversary of Killing Is My Business... and Business Is Good! before Mustaine's cancer diagnosis.
In his statement, the frontman vowed he would be "back on the road asap".