Incidence of Right-Sided Colon Cancer After Negative Colonoscopy

We know that some patients develop colorectal cancers (CRCs) even after negative colonoscopies. A recent study from Manitoba, Canada (JW Gastroenterol Jun 13 2008), and an abstracted study from California showed that colonoscopy provided less protection against proximal colon cancers than against left-sided disease. Now, a group of researchers from Ontario, Canada, have confirmed these results.

Using linked administrative databases, researchers identified a cohort of 110,402 people who had negative complete colonoscopies performed between 1992 and 1997. The remaining population in the databases served as controls. The index colonoscopy was defined as negative if no biopsy or polypectomy was performed, no second colonoscopy was performed with…