The 57-year-old singer played the cop and naval officer personas for the group, Wikipedia said.
Contactmusic.com reported that Willis canceled his U.S. summer tour because of the surgery he underwent Monday at a San Diego hospital.
His spokeswoman, Linda Smith, told the music news Web site that Willis is expected to make a full recovery and is hoping to be back on stage in October.
"Victor's surgery was a success and the benign nodules were successfully removed," Smith said.
Ray Liotta sues skin care company over use of likeness
Boston schools pull out free condoms over wrapping complaints