Maureen Reagan is hospitalized and receiving radiation for melanoma that has spread to her brain, her husband said Friday.
Reagan, 60, is the daughter of former President Ronald Reagan and actress Jane Wyman. She is battling for her life at Mercy San Juan Hospital in Carmichael, near the family's Northern California home.
Last November, a golf ball-sized malignant tumor was discovered in her right pubic bone and she underwent 3 ½ months of aggressive biochemotherapy treatments at the John Wayne Cancer Institute at Saint John's Health Center in Santa Monica.
She appeared to be winning her cancer fight when she was released from the Santa Monica hospital on March 23. She returned to her Sacramento-area home and was put on a 12-month, self-administered biotherapy program, her husband of 20 years, Dennis C. Revell said.
Reagan was stricken with mild seizures on the Fourth of July and a MRI performed July 6 confirmed two brain tumors, Revell said in a detailed statement.
She was diagnosed with melanoma, the deadliest form of skin cancer, on Dec. 12, 1996. Revell said the five-year survival rate for melanoma that has widely spread is less than 20 percent.
"She believes that there are many factors that help a person survive, from the power of one's faith and prayers to support of family and friends to the quality of one's medical care to maintaining a positive attitude," Revell said.
"Like many cancer patients, Maureen prefers not to dwell on the statistical survival rates, preferring to recognize that each person's case is quite different and unique," said Revell, who has been at his wife's side throughout her hospitalizations.
Jane Wyman and former first lady Nancy Reagan have visited her.
"I saw her a little over a week ago and told her that her dad and I love her and we're praying for her every day," Nancy Reagan said.
The former president's eldest daughter became a national spokeswoman for the Alzheimer's Association after her father announced in 1994 that he had the disease and was beginning "the journey that will lead me into the sunset of my life."
She traveled the U.S. to speak about Alzheimer's patients and their caregivers. She testified before Congress to get more funds for research and family support.
"Our prayers are with Maureen," Orien Reid, chairman of the association's national board of directors, said in a statement in response to her latest cancer setback. "We are grateful to Maureen for her passion and commitment to fighting Alzheimer's disease."
In addition to Alzheimer's disease, she was dedicated to raising public awareness of melanoma, and promoting the importance of skin examinations.
Melanoma is the fastest growing cancer in the United States. About 8,000 people in this country die from it every year, and almost 40,000 new cases are diagnosed each year.
The Associated Press contributed to this report.