U.S. Supreme Court Justice Ruth Bader Ginsburg was successfully treated for a malignant tumor on her pancreas, the court said in a statement Friday, in the latest health scare for the court’s oldest member and liberal leader.

The 86-year-old justice completed a three-week course of radiation therapy at Memorial Sloan Kettering Cancer Center in New York and no further treatment is needed at this point, the statement said.

“The abnormality was first detected after a routine blood test in early July,” the court statement said. “The tumor was treated definitively and there is no evidence of disease elsewhere in the...