WASHINGTON —  Chief Justice William H. Rehnquist (search) will not preside on Monday when the Supreme Court returns from the holidays, a court spokeswoman said Friday.

Rehnquist, who has thyroid cancer (search), missed about 25 cases that were argued in November and December while receiving chemotherapy and radiation.

The 80-year-old chief justice was diagnosed with the disease in October and worked from home for two months after being hospitalized and undergoing a tracheotomy to help him breathe.

Supreme Court spokeswoman Kathy Arberg said that he would not be able to return to the bench "because of continuing secretions caused by his tracheotomy and radiation therapy."

Rehnquist has been coming to the court periodically since the week of Dec. 20. His 33rd anniversary on the court was Friday.

"He will continue to read briefs and transcripts of oral arguments, participate in conferences, and vote on cases," Arberg said.

Rehnquist is still expected to administer the oath of office (search) to President Bush on Jan. 20, if his health permits it.