Former President Ronald Reagan's daughter Maureen is in hospital undergoing treatment for cancer that has spread since she was diagnosed with melanoma four years ago.
Surgeons removed a golf ball-sized malignant tumour from her pelvis and removed all the lymph nodes between her right knee and groin in November, doctors in Santa Monica, California said.
Reagan, daughter of the former president and actress Jane Wyman, was 60 last Thursday and is a national spokeswoman and board member of the Chicago-based Alzheimer's Association. Her father has Alzheimer's disease.
She entered the John Wayne Cancer Institute on December 11 to begin the aggressive cancer-fighting treatments, said Danny Chun, a spokesman for the Alzheimer's Association.
Her husband, Dennis Revell, is with her at the hospital.
Dr Steven O'Day, the institute's director of medical oncology, said: "While her progress is still guarded, she is a surprisingly strong and resilient individual and has tolerated the therapy very well."