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An interval cancer is one diagnosed after a screening test or a colonoscopy that found nothing, and before the next test was due. Every screening programme has them. Counting them honestly is how a programme finds out what it is missing, and in the bowel most of them come from lesions that were there and were not seen.
The definition. The World Endoscopy Organization's expert group defined an interval colorectal cancer as a cancer diagnosed after a screening or surveillance examination in which no cancer was found, and before the date of the next recommended examination, and separated it in the taxonomy from a cancer found after a test was declined or after a scheduled test was missed (Sanduleanu 2015). The standardised nomenclature exists so that programmes in different countries can compare their rates at all.
Where they come from. Most post-colonoscopy colorectal cancers are attributed to lesions that were present and missed or incompletely removed rather than to genuinely fast new growth, which is why the adenoma detection rate predicts them so strongly: across 314,872 colonoscopies, the risk of interval cancer fell from 9.8 to 4.8 cases per 10,000 person-years across the fifths of detection rate (Corley 2014). Flat and serrated lesions are over-represented because they are pale, flat and often covered by mucus, and because they bleed too little for a stool test to catch them.
What it means for a reader. A normal test is reassurance, not a guarantee. Symptoms after a negative screening result still need investigating, which is why NICE NG12 (1.3.1) says to offer a faecal immunochemical test even to someone who had a negative screening result. For a programme, the interval cancer rate is the number that decides whether the screening interval and the test threshold are right.
Showing the technology this term belongs to: Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood).
Shares Adenoma detection rate, Surveillance intervals after polypectomy, Serrated pathway, Colonoscopy and the tags gi, colorectal.
Shares Surveillance intervals after polypectomy, Serrated pathway, Colonoscopy, Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood) and the tags gi, colorectal.
Shares Serrated pathway, Colon cancer (adenocarcinoma of the colon), Colorectal cancer and the tags gi, colorectal.
Shares Colon cancer (adenocarcinoma of the colon), Rectal cancer, Colorectal cancer and the tags gi, colorectal.
Shares Colonoscopy, Colorectal cancer and the tags gi, colorectal.
Shares Colon cancer (adenocarcinoma of the colon), Rectal cancer, Colorectal cancer and the tags gi, colorectal.
Shares Colon cancer (adenocarcinoma of the colon), Rectal cancer, Colorectal cancer and the tags gi, colorectal.
Shares Colon cancer (adenocarcinoma of the colon), Rectal cancer, Colorectal cancer and the tags gi, colorectal.