Dr. Alfred Knudson

Alfred Knudson, pioneer of cancer genetics, has died at the age of 93, according to multiple news sources.

Knudson died after a long illness, according to a funeral home and the Fox Chase Cancer Center where he worked for decades.

The geneticist was known for his two-hit hypothesis, published in 1971. He researched children with retinoblastoma, a rare cancer of the eye. His study believed that people with hereditary cancers inherit one copy of a damaged gene, the first hit, but develop cancer only if they develop a second hit, the loss of the good copy in a gene pair. This is different than people who develop nonhereditary forms of cancer as they must get both hits, meaning cancers usually occur later in life.

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The American Society of Clinical Oncology called Knudson "a pioneering cancer geneticist" and credited him with "helping to usher in a new era of research on tumor suppressor genes."

He was the recipient of major medical awards, including the 2004 Kyoto Prize, the 1998 Albert Lasker Clinical Medical Research Award, the American Society of Hematology's Distinguished Career Award and the American Association for Cancer Research Award for Lifetime Achievement in Cancer Research.

He was born in Los Angeles and received his M.D. from Columbia University.

He is survived by his wife and three daughters from a previous marriage.