Two new DNA-tests could help detect early cases of colon cancer, and maybe even sharply reduce the number of cases, the New York Times reports. Colonoscopies are now routinely prescribed for people over 50, but instead of screening the entire population, doctors might refer them to have the test only if they tested positive on one of the DNA tests. One looks at stool samples for four altered genes that point to the cancer, and could catch cancerous and precancerous tumours at an early stage when they’re still curable. The other looks at blood for changes to one gene. Both would be less expensive than a colonoscopy, and maybe more effective.