Colonoscopies save lives. Why did a trial suggest they might not?

Emily Sohn in Nature:

It was an uncomfortable moment for people who perform colonoscopies. In October, a massive randomized clinical trial in Europe presented its initial results1, which suggested that, as a screening tool, colonoscopies don’t save as many lives as expected. Researchers were perplexed because the procedure had long been considered a true success story in cancer screening. But after the study results were compared with data from other trials, colonoscopy to be seemed less effective than simpler screening methods that assess only part of the colon. Jason Dominitz, a physician at the Veterans Health Administration in Seattle, Washington, says it was like suggesting that mammography on only one breast was better than scanning both. It didn’t make sense.

A media frenzy followed, and headlines were blunt, declaring that colonoscopies might not be effective or prevent deaths at all. But when Dominitz dug deeper, the trial results reflected where and how the study was conducted and the complexity of the questions it was trying to answer. “It is really important to not just read the headline,” says Dominitz, who is also director of the colorectal-cancer screening programme run by the US Department of Veteran Affairs.

More here.