CNN confirms. He passed away in a Massachusetts hospital, according to bandmate Brad Fischetti. Cronin, who wrote and sang the number one smash "Summer Girls," was diagnosed with leukemia in 2005; despite chemotherapy, the disease returned in 2007 and 2008.
The singer-songwriter then underwent a stem cell transplant -- which, according to Fischetti, led to a stroke and severe leg pain.
Even with his medical battles, Cronin reunited with LFO pals Fischetti and Devin Lima for a summer 2009 tour.
His bandmates gave him a large back bedroom on the bus so he could rest in between gigs.
"We had the best time ever," Fischetti said. "He never thought he'd be on stage again."
- Rich Cronin