Lead guitarist The Edge from Irish rock band sensation U2 played “the most beautiful parish hall in the world” this weekend — the Sistine Chapel.

The performance, the first-ever rock concert in the historic chapel, was given for about 200 doctors researchers who attended a conference at the Vatican last week on regenerative medicine. The conference discussed the use of adult stem cells to cure difficult and rare diseases such as cancer.

The Edge, whose real name is David Evans, wore his signature black beanie while he played and sang a cover of Leonard Cohen’s “If it be your will,” and renditions of U2 songs “Yahweh,” “Ordinary love” and “Walk on.”

The rock star, who has experienced the effects of cancer in his own life — his father died from cancer last month and his daughter once had leukemia — peppered his performance with references to some technical cancer terms.

“I can tell this is a really cool audience because normally when I say ‘angiogenesis,’ eyes glaze over,” he said, according to Reuters. Angiogenesis is the process through which new blood vessels are formed that feed the growth of tumors. Researchers and scientists are looking for ways to prevent angiogenesis.

The Edge, who was accompanied by a choir of seven Irish teenagers during his performance, also joked that he was a bit shocked when he was asked to play and sing at the Vatican.  

“When they asked me if I wanted to become the first contemporary artist to play in the Sistine Chapel, I didn’t know what to say because usually there’s this other guy who sings,” he said, referring to U2’s lead singer Bono.

He also thanked Pope Francis and Vatican officials for allowing him to play in “the most beautiful parish hall in the world.”

“Being Irish you learn very early that if you want to be asked to come back it’s very important to thank the local parish priest for the loan of the hall,” he said.

The singer dedicated his performance of the 2000 song “Walk On” to Pope Francis, who he called “the people’s pope.”

“He’s doing an amazing job and long may he continue,” he said.

The Cellular Horizons conference was hosted at the Vatican by the U.S.-based Stem for Life Foundation. Speakers at the conference included Pope Francis and U.S. Vice President Joe Biden, who is advocating for a global push to end cancer.