Kennedy aides said radiation and chemotherapy treatments at Massachusetts General Hospital in Boston are progressing but doctors recommended Kennedy delay returning to Washington, The Washington Post reported Monday.

Kennedy underwent brain surgery June 2 at Duke University Medical Center in Durham, N.C., to remove a malignant tumor.

Since his operation, Kennedy has made two public appearances: One in July when he returned to the Senate for a vote on Medicare price issues and Aug. 25 when he spoke at the Democratic National Convention in Denver.