Peter Nowell, a medical researcher who, in the simple process of cleaning slides bearing leukemic cells, helped uncover the first clear sign of a genetic cause of cancer, died Dec. 26 in Newtown Square, Pennsylvania. He was 88.

The cause was complications from Alzheimer’s disease, said a daughter, Kristin Nowell.

Peter Nowell

Peter Nowell University of Pennsylvania photo

Nowell, who spent nearly his entire career at the University of Pennsylvania, was working in a laboratory there in the late 1950s when he made his seminal discovery. He was studying samples of chronic myeloid leukemia – a disorder of the blood and bone marrow then considered a death sentence – and happened to wash his slides with tap water instead of a laboratory solution.

Viewing the newly cleaned slides under a microscope, he saw that the water had caused the cell’s chromosomes, the threadlike carriers of genes, to expand.

“I didn’t know anything about chromosomes,” he told the Philadelphia Inquirer years later, “but it seemed a shame to throw this away.”

Dr. Nowell partnered with David Hungerford, a graduate student at the Fox Chase Cancer Center in Philadelphia. Analyzing the white blood cells of patients with this particular form of leukemia, Hungerford noticed a consistent aberration: One of the 46 chromosomes, the 22nd, was noticeably short. The chromosome was named the Philadelphia chromosome, for the city where the research took place.

“Every cell had it, and it was there in every typical case” of the condition, Nowell told a publication of the University of Pennsylvania. “So that argued both for, one, a genetic change as being important in the development of this form of cancer, and, two, that tumors might indeed arise from a single cell in which such a change occurred.”

The finding was a turning point. Until then, most scientists believed viruses to be the cause of cancer.

“In those days, we really knew nothing about the fundamental nature of cancer,” Nowell recalled. Furthermore, he said, “a lot of people didn’t want to believe [the finding] at the time, because they preferred that cancer should result from changes that did not involve the genetic material of the cell, because it would be easier to reverse.”

Nowell’s work fueled decades of scientific research that produced monumental steps in the treatment of cancer.

Gradually, technology improved enough to allow scientists to visualize the genetic material in greater detail. Janet Rowley, a researcher at the University of Chicago, would identify the Philadelphia chromosome as the product of a translocation, in which portions of two chromosomes exchange places, causing cells to turn malignant. Alfred Knudson, a geneticist at Fox Chase, made further progress linking genetics and cancer.

In 1998, Nowell, Rowley and Knudson received Lasker Awards, commonly known as the American Nobel. With drugs such as Gleevec, chronic myeloid leukemia can be held in remission for years. “That was the good news,” Nowell said, referring to the advances precipitated by his collaboration with Hungerford. But the field of cancer research remained dauntingly complex.

“The bad news,” he said, “was that as we and others did this over the next decade, it turned out that there were 20 or 30 or 50 different genes just producing different kinds of leukemia.”

Peter Carey Nowell was born on Feb. 8, 1928, in Philadelphia. His mother was a writer and a teacher, and his father was an electrical engineer for the Bell telephone company.

He received a bachelor’s degree in biology and chemistry from Wesleyan University in Middletown, Connecticut, in 1948 and a medical degree from the University of Pennsylvania four years later. In the early years of his career, while serving in the Navy, he conducted research at the Naval Radiological Defense Laboratory in San Francisco.

Nowell joined the University of Pennsylvania faculty in 1956 and was a chairman of the department of pathology and laboratory medicine. The school credited him for advances in the stimulation of cell division for laboratory study, as well as for insights involving bone-marrow transplants and the role of radiation in causing cancer.

His wife of 54 years, Helen Walker Worst, died in 2004. Their daughter Sharon Nowell, who suffered from cerebral palsy, died in 2000.

Survivors include four children, Timothy Nowell of Thornton, Pennsylvania, Karen King of Felton, Delaware, Kristin Nowell of Wallingford, Pennsylvania, and Michael Nowell of Swarthmore, Pennsylvania..

Nowell once reflected on the accidental nature of his discovery. It came about, he remarked to the Lasker Foundation, because he was simply “diddling around with leukemic cells in culture.” “Serendipity plays a major role in biological progress,” he told the U-Penn. publication.