Colonoscopy misses 6% of cancers

The term 'missed' indicated that cancer or precancerous polyps were present but not seen, and also included cancers that had no visible evidence at the time of colonoscopy but developed rapidly afterwards.

Researchers from the US examined data for all patients who had colonoscopies performed at a single centre over a 14-year period and found that a number of factors were typically associated with missed cancers.

They tended to appear in patients over the age of 65, with a family history of colorectal cancer, who were previously diagnosed with polyps. 

The missed cancers were also more likely to appear in the right side of the colon, at the far end of the colonoscope’s reach, the authors said. 

They said cancers that occur in the right side of the colon are often biologically different to those in other parts which arise from different types of polyps.

“These types of polyps are flatter and faster growing,