Mrs. Stovall, center, died Jan. 5, 2016, at 69. (National Coalition for Cancer Survivorship)

Ellen Stovall was 24 and the mother of a newborn boy when she learned that she had Stage 4 Hodgkin’s lymphoma. Her reaction was “absolute, abject terror that I wouldn’t be here to be with my family, to raise my son,” she told The Washington Post years later, and “absolute determination that I had to be here.”

She began treatment Dec. 23, 1971, the day President Richard M. Nixon signed the National Cancer Act, launching what became known as the war on cancer. She pledged that if she lived two years beyond her diagnosis, she would use her remaining time to improve the lives of people with the disease.

Mrs. Stovall died Jan. 5 at a hospital in Rockville, Md. She was 69, a three-time cancer patient, and was nationally known among physicians, legislators and policymakers as one of the country’s most forceful advocates for cancer survivors. And they were survivors, she emphasized — not victims.

“Survivorship became what I did,” she said. “I lived with the cancer, I lived through the cancer, and I lived beyond the cancer. Survivorship became a way that I lived my life after the cancer. I live with the fact that I had cancer, and that knowledge has been empowering for me.”

Mrs. Stovall’s death was announced by the National Coalition for Cancer Survivorship, where she was president and chief executive from 1992 to 2008 and later a senior health policy adviser. Her brother, Stephen Lewis, said she had cardiac ailments related to her radiation and chemotherapy decades ago.

Mrs. Stovall began her advocacy work soon after she first became ill, starting a support group for young cancer patients at Georgetown University’s hospital. After successful treatment, she suffered a relapse 12 years later.

Around that time, she became involved with the cancer coalition, then based in Albuquerque. Its mission, according to its website, was to extend cancer care beyond diagnosis and treatment to the tenuous period when the disease is in remission — at bay, but ever present.

When the coalition moved to the Washington area in 1992, Mrs. Stovall became president and one of its most visible representatives. She testified before Congress and led events, including a 1998 rally on the National Mall that drew a crowd of 150,000 or more, according to organizers’ estimates.

President Bill Clinton named her to the National Cancer Advisory Board at the National Cancer Institute, where she helped establish the Office of Cancer Survivorship in 1996. In 2005, she helped write a report called “From Cancer Patient to Cancer Survivor: Lost in Transition.”

By that time, many cancer patients could look forward to longer lives, thanks to the advance of medical science, but their needs were poorly understood, Mrs. Stovall said.

“You get the pat on the back for taking chemo and going bald,” she told the Dallas Morning News. Surviving, she said, “is one of those issues that make people yawn.”

She and other advocates drew attention to the chronic pain, infertility, paralysis and other problems that afflict many patients who have undergone cancer-related surgery, radiation or other treatment. Mrs. Stovall also gave voice to the psychological burden carried by survivors, who at any time may face a relapse.

“The fear of recurrence is just an overwhelming fear, even if they have been told that there is just this very good chance that they will be here for a long time,” Mrs. Stovall told The Post. “You never lose it.”

In 2007, Mrs. Stovall had a mastectomy after receiving a diagnosis of early breast cancer, linked, like her heart ailments, to her earlier treatments. For herself and for other cancer patients, she had sought to maintain realistic expectations. The word “cure,” she said, is in many cases “preposterous.”

But “life,” she observed, is also “a death sentence.”

Ellen Roos Lewis was born in Scranton, Pa., on Dec. 2, 1946. She attended Pennsylvania State University, married and settled in Gaithersburg, Md.

She said she had symptoms for four years of the disease that would be diagnosed as Hodgkin’s: itching mistaken for allergies, three miscarriages and anemia. A doctor prescribed Valium and, by her account, “patted me on the head and said, ‘Go home, little girl.’ ”

She found relief in the clarity of her diagnosis, she said, but little comfort in her prognosis — by one estimate, a less than 20 percent chance of survival. One doctor told her, “Why do you want statistics? It’s either 100 percent or nothing for you.”

Besides her brother, survivors include her husband of 46 years, John Stovall of Gaithersburg; and a son, Jonathan Stovall of Chevy Chase, Md.

Mrs. Stovall said that cancer, and living with it, had made her a different person from the one she might otherwise have been. When she subscribed to a magazine, she committed to six months, not 12. She did not plan vacations a year in advance. At the same time, she said, cancer had made her more adventurous — more willing to go white-water rafting or bungee jumping.

“I have more of a spirit of adventure. I am not as cautious,” she told The Post. “I could walk out on the street and get hit by the Number 52 bus. I am probably going to die of cancer, but maybe not. So why not try some things?”