Genetic testing is becoming cheaper and more widespread, promising to usher in a revolution in cancer treatment. Yet, long-standing DNA tests are often overlooked for reasons including doctors’ ignorance and financial incentives discouraging companies from marketing them. Fifty years ago, Henry T. Lynch, then a medical resident in Nebraska, started tracking families with a high incidence of colon cancer and other tumors. While some were skeptical when he suggested the risks were inherited, geneticists proved him right in the mid-1990s by finding the genes that caused the condition. Lynch syndrome may account for about 3 percent of all colon cancer, or more than 4,000 cases a year in the U.S., said Heather Hampel, an Ohio State University genetic counselor.
