Hubert Humphrey might not have run for president against Richard Nixon in 1968 if scientists knew then what they know now.
By analyzing bladder tissue taken from a urine sample Humphrey gave in 1967, when he was vice president, two scientists have pinpointed the genetic defect that caused his fatal bladder cancer.Some doctors suspected in 1967 that Humphrey had bladder cancer, but others disagreed and he was not treated. He went on to win the Democratic presidential nomination and narrowly lost the general election to Nixon.
If the genetic test had been available to let Humphrey know he was at high risk of developing cancer, he might not have run against Nixon, said the study by Drs. David Sidransky and Ralph H. Hruban of Johns Hopkins University.
"I would have resigned the nomination immediately I knew of my illness," Humphrey told a biographer after the first clear signs of his cancer were discovered in 1969. He died of the disease in 1978.
The doctors' study was published in Thursday's issue of the New England Journal of Medicine.
"It showed definitively that we can pick up cancer years before the tumor is found by normal clinical methods," Sidransky said. Humphrey had sought medical advice in 1967 for blood in his urine.
Scientists now know that cancer is triggered by a series of genetic defects acquired over a lifetime that can precede obvious cancer by many years.
One of the most common mistakes is the mutation of a gene called p53, which is supposed to stop cells from dividing when other genes go awry. When the p53 gene is defective, cells lose their internal control over growth and cancer can ensue. This is what happened to Humphrey, the Hopkins researchers said.
Even today, it's unclear what doctors would tell an outwardly healthy patient whose bladder cells contained mutant p53, said Dr. John Gribben of the Dana-Farber Cancer Institute in Boston.
Many speculate that screening people for so-called cancer genes will someday be an important way to head off cancer. But Gribben cautioned that doctors cannot be sure those who have these mutations will actually get the disease.
"It's fascinating and the way we probably will go in the future," he said. "But we are not there yet. We don't know what to make of that knowledge."
No test yet exists that can easily search for a mistake in the p53 gene without knowing in advance which error to look for.