In a time when many heavy metal heroes have begun to experience serious health issues, Iron Maiden fans rejoiced when vocalist Bruce Dickinson bounced back from his cancer battle after being given the "all clear" from doctors. In a new interview, however, drummer Nicko McBrain admitted that he at one point thought Iron Maiden was finished.

Bruce put off seeing a doctor until The Book of Souls was recorded in full, being diagnosed with tongue and throat cancer immediately after. Dickinson knew that cancer was the likely prognosis during the Book of Souls sessions, but his fellow bandmates were somewhat unaware. "Do you know that none of us knew that he was [doing] poorly, until after the record was done? He performed that whole album, knowing that something wasn’t quite right with himself, but didn’t get diagnosed till after we’d finished the tracks," McBrain tells Overdrive. "So this album Book of Souls is just very special to me and all the rest of the guys. Bruce didn’t know until December 2014 and then started his treatment in January 2015. We weren’t aware and neither was he, that he had the tumor."

McBrain speaks about thinking the worst for Iron Maiden and praying to God for his good friend and bandmate, "I’d be a liar if I didn’t think for a minute that Iron Maiden's finished, I thought more about the possibility of losing my friend than anything else, to be honest. Then later I was thinking, God forbid if the worst ever happened, the legacy would be the last 16 albums. I’ve got to be honest, I did question his mortality at one point and thankfully that didn’t last long. Honestly, I got down on my knees and said a prayer, picked my thoughts up and got positive about it all thinking to myself, 'If anyone can beat this, its Bruce!' He’s so positive about everything he’s ever done in his life, or what every he is about to do. Basically, I prayed for him and my prayers were answered, as well as everybody else that knows and cares for him.

The Book of Souls debuted at No. 4 in the U.S. selling a first-week total of 75,000 copies. Iron Maiden also topped the charts in their homeland of the U.K. along with 14 other countries.

See the Yearbook Photos of Bruce Dickinson + Other Rock Stars

Iron Maiden's Bruce Dickinson Opens Up on Cancer Battle