“He had the only kind of pancreatic cancer that is treatable and curable,” she told USA Today in 2013. “He essentially committed suicide.”

But Dr. Cassileth was also quick to note the limits of her own research, and to assert her openness to the possible efficacy of treatments outside the mainstream. She was both a member the American Cancer Society’s Subcommittee on Questionable Methods of Cancer Management and an adviser to the National Institutes of Health’s Office of Alternative Medicine, now called the National Center for Complementary and Alternative Medicine.

She took a historical perspective. Cancer was once considered incurable, and so the focus of treatment was limited to palliative care, helping to ease a patient’s pain. But with the rise of chemotherapy and radiation and the growing possibility of survival, comfort and quality of life took a back seat. Her mission, she said, was to bring that back, using evidence-based, noninvasive treatments.

“She was a legend in our field,” Dr. Ting Bao, the director of integrative breast oncology at Memorial Sloan Kettering, said in an interview.

Barrie Joyce Rabinowitz was born on April 22, 1938, in Philadelphia. Her father, Albert Rabinowitz, owned a company that manufactured socks; later, he and her mother, Rosalind (Kaizen) Rabinowitz, ran a company that designed and installed kitchens.

She is survived by her siblings, Stephen and Ruth Rabinowitz; her daughters, Jodi Cassileth Greenspan and Wendy Cassileth; her son, Gregory Cassileth; and six grandchildren.

Dr. Cassileth attended Bennington College in Vermont and spent a summer teaching art in Pownal, a village near the Massachusetts border. Working out of a one-room schoolhouse, she befriended the parents of two of her students. The mother, Ms. Rabinowitz soon learned, had terminal cancer, and the experience of watching her suffer focused her interests on helping to alleviate such pain.