Thomas joined the faculty of Fred Hutchinson Cancer Research Center in 1974 as its first director of medical oncology. He later became associate director and eventually director of the Center's Clinical Research Division. He stepped down from that position at age 70 in 1990 and officially retired from the Hutchinson Center in 2002.

Thomas, along with his wife and research partner, Dottie – a trained medical technologist – and a small team of fellow researchers stubbornly pursued transplantation throughout the 1960s and 1970s despite doubts by many prominent physicians of the day.

"To the world, Don Thomas will forever be known as the father of bone marrow transplantation, but to his colleagues at Fred Hutch he will be remembered as a friend, colleague, mentor and pioneer," said Larry Corey, M.D., president and director of Fred Hutchinson Cancer Research Center. "The work Don Thomas did to establish marrow transplantation as a successful treatment for leukemia and other otherwise fatal diseases of the blood is responsible for saving the lives of hundreds of thousands of people around the globe."

His groundbreaking work is among the greatest success stories in cancer treatment. Bone marrow transplantation and its sister therapy, blood stem cell transplantation, have had worldwide impact, boosting survival rates from nearly zero to up to 90 percent for some blood cancers. This year, approximately 60,000 transplants will be performed worldwide.

Thomas edited the first two editions of the seminal bone marrow transplantation reference book, "Hematopoietic Cell Transplantation," in 1994 and 1999, which became recognized as the "bible in the field." He also contributed a chapter to the third edition, published in 2004, at which time the book's title was changed to "Thomas' Hematopoietic Cell Transplantation."

"Don quite literally wrote the book on marrow transplantation," said Fred Appelbaum, M.D., director of the Hutchinson Center's Clinical Research Division, a friend of Thomas' and an editor of the book. "Don was a hero. He was, by far, the most influential person in my career, and I know that many others would say the same thing."

Thomas was a member of 15 medical societies, including the National Academy of Sciences. He also received more than 35 major honors and awards, including the Gairdner Foundation International Award and the Presidential Medal of Science. He was past president of the American Society of Hematology and served on the editorial boards of eight medical journals.

Thomas came to Seattle in 1963 to be the first head of the Division of Oncology at the University of Washington School of Medicine. Continuing work begun in Cooperstown, N.Y., Thomas led a small team that labored in the basement of temporary facilities at the former U.S. Public Health Hospital. They sought to do what others were convinced would never work: to cure leukemia and other cancers of the blood by destroying a patient's diseased bone marrow with near-lethal doses of radiation and chemotherapy and then rescuing the patient by transplanting healthy marrow. The goal was to establish a fully functioning and cancer-free blood and immune system.

"We moved to Seattle … at a time when it seemed that marrow transplantation would never be successful," Thomas recalled in a 2000 interview. "So we focused our attention on laboratory experiments." As chief of medicine at the Mary Imogene Bassett Hospital in Cooperstown, N.Y., Thomas began studies of marrow grafts, treating relatively few human patients. After moving to Seattle, Thomas and his colleagues worked almost exclusively in the laboratory well into 1967, postponing work on patients until treatment complications could be resolved.

It took almost 20 years after Thomas's seminal paper on bone-marrow transplantation was published in The New England Journal of Medicine in September 1957 for the procedure to become an accepted therapy. During that time most medical professionals dismissed the idea.

"In the 1960s in particular and even into the 1970s, there were very responsible physicians who said this would never work," Thomas said. "Some suggested it shouldn't go on as an experimental thing."

The early success was enough to convince Seattle surgeon William Hutchinson, M.D., to support Thomas and his team and build the group a permanent home. In 1972, ground broke for the construction of the original Fred Hutchinson Cancer Research Center building in Seattle's First Hill neighborhood, and its doors opened in 1975.

Thomas and his team persisted because they believed transplantation was the key to saving the lives of people with leukemia, lymphoma, multiple myeloma and other fatal blood diseases.

"I've said in the past that I have two attributes: one is I'm stubborn to keep doing it and other is I attracted some good people to work with me," Thomas told an interviewer in 2006.

Today, bone marrow transplants are a proven success for treating leukemia and other cancers as well as blood disorders such as aplastic anemia.

Thomas is survived by his wife, Dottie, two sons and a daughter.

To make a donation in Thomas' memory and continue the legacy of his lifesaving research, visit http://getinvolved.fhcrc.org/thomas here. Gifts will be directed to the Clinical Research Division, of which Thomas was the founding director.