The cause was complications of pneumonia, his son, Thomas Jensen, said.
In 2004 Dr. Jensen received the Albert Lasker Basic Medical Research Award, one of the most respected science prizes in the world.
When Dr. Jensen started his research at the University of Chicago in the 1950s, steroid hormones, which alter the functioning of cells, were thought to interact with cells through a series of chemical reactions involving enzymes.
However, Dr. Jensen used radioactive tracers to show that steroid hormones actually affect cells by binding to a specific receptor protein inside them. He first focused on the steroid hormone estrogen.
By 1968, Dr. Jensen had developed a test for the presence of estrogen receptors in breast cancer cells. He later concluded that such receptors were present in about a third of those cells.
Breast cancers that are estrogen positive, meaning they have receptors for the hormone, can be treated with medications like Tamoxifen or with other methods of inhibiting estrogen in a patient’s system, like removal of the ovaries. Women with receptor-rich breast cancers often go into remission when estrogen is blocked or removed.
By the mid-1980s, a test developed by Dr. Jensen and a colleague at the University of Chicago, Dr. Geoffrey Greene, could be used to determine the extent of estrogen receptors in breast and other cancers. That test became a standard part of care for breast cancer patients.
Scientists like Dr. Pierre Chambon and Dr. Ronald M. Evans, who shared the 2004 Lasker prize with Dr. Jensen, went on to show that many types of receptors exist. The receptors are crucial components of the cell’s control system and transmit signals in an array of vital functions, from the development of organs in the womb to the control of fat cells and the regulation of cholesterol.
Dr. Jensen’s work also led to the development of drugs that can enhance or inhibit the effects of hormones. Such drugs are used to treat prostate and other cancers.
Elwood Vernon Jensen was born in Fargo, N.D., on Jan. 13, 1920, to Eli and Vera Morris Jensen. He majored in chemistry at what was then Wittenberg College in Springfield, Ohio, and had begun graduate training in organic chemistry at the University of Chicago when World War II began.
Dr. Jensen wanted to join the Army Air Forces, but his poor vision kept him from becoming a pilot. During the war he synthesized poison gases at the University of Chicago, exposure to which twice put him in the hospital. His work on toxic chemicals, he said, inspired him to pursue biology and medicine.
Dr. Jensen studied steroid hormone chemistry at the Swiss Federal Institute of Technology on a Guggenheim Fellowship after the war. While there, he climbed the Matterhorn, one of the highest peaks in the Alps, even though he had no mountaineering experience. He often equated his successful research to the novel approach taken by Edward Whymper, the first mountaineer to reach the Matterhorn’s summit. Mr. Whymper went against conventional wisdom and scaled the mountain’s Swiss face, after twice failing to reach the summit on the Italian side.
Dr. Jensen joined the University of Chicago as an assistant professor of surgery in 1947, working closely with the Nobel laureate Charles Huggins. He became an original member of the research team at the Ben May Laboratory for Cancer Research (now the Ben May Department for Cancer Research) in 1951, and became the director after Dr. Huggins stepped down.
He came to work at the University of Cincinnati in 2002, and continued to do research there until last year.
His first wife, the former Mary Collette, died in 1982. In addition to his son, Dr. Jensen is survived by his second wife, the former Hiltrud Herborg; a daughter, Karen C. Jensen; a sister, Margaret Brennan; two grandchildren; and three great-grandchildren.
Dr. Jensen’s wife was found to have breast cancer in 2005. She had the tumor removed, he said in an interview, but tested positive for the estrogen receptor and was successfully treated with a medication that prevents estrogen synthesis.
