The 69-year-old Spanish tenor became ill on tour in Tokyo, had surgery early this month at Mount Sinai Hospital in New York and has been recuperating in Acapulco, Mexico.
He returned to Los Angeles on Thursday and a few hours later was back at work as director of the Los Angeles Opera Company.
Domingo told reporters during a break he planned to begin rehearsals for "Simon Boccanegra" at Italy's La Scala in two weeks.
The malignancy was localized so Domingo was able to undergo minimally invasive surgery to remove the polyp.
