WIKIMEDIA, NATIONAL CANCER INSTITUTEAlfred Knudson, best known for revealing through mathematics how cancers emerge, died July 10, according to a statement by the Fox Chase Cancer Center in Philadelphia. His wife, Anna Meadows, told the The Washington Post that he had heart ailments and dementia. He was 93.
In 1971, Knudson published an article that unlocked a key question in oncology: How does cancer begin? By analyzing the distribution of children with retinoblastoma—a rare cancer of the eye—with a statistical model, he devised what came to be known as the “two-hit” hypothesis.
The cancer arose when a tumor suppressor gene had undergone two mutations. This explained the two major types of retinoblastoma patients. Some children had inherited one mutation, the first hit, from their healthy parents and, being predisposed, developed multiple tumors in both eyes when radiation of a replication mistake introduced another mutation—the second hit. But other children generally presented a tumor in just one eye at an older age. These patients would have initially carried no mutation, making the chances of ...
