EP.TU.660The rate of interval colorectal cancer within 5 years of a negative colonoscopy at a district general hospital

Aims Interval colorectal cancer is defined as cancer that has developed within a short interval of a diagnostic test that did not detect a cancer. Many authors define this interval as five years, though more complex definitions of interval cancer have been proposed. Our aim was to determine what percentage of colorectal cancers diagnosed at our hospital had a negative colonoscopy within the 5 years prior to their diagnosis. Methods We obtained details of all colorectal cancers diagnosed between 2017-2019 at our department. We then surveyed the endoscopy system to detect the patients who had a negative colonoscopy within the 5 years prior to their diagnosis, to calculate what percentage of cancers diagnosed within that period were interval cancers. Results Between 2017-2019, 539 patients were diagnosed with colorectal cancer. Age at diagnosis varied widely from 21 to 107, and 310 (57.5%) of patients were male. Seventeen patients had a negative colonoscopy within 5 years (though two of these were planned repeat procedures within a few months of the index ‘negative’ colonoscopy). We can therefore calculate the rate of interval cancer at 3.1% between 2017-2019. Conclusions The aetiology of interval colorectal cancer has been attributed to patient/tumour factors (right colon and female sex) and technical factors (adenoma detection and caecal intubation rate). Though the rate of interval cancer at our department seems pleasingly low compared to the literature, we plan to investigate the risk factors that might be at play: are biological factors to blame or can our endoscopy service be improved?

Future Prospects of Colorectal Cancer Screening: Characterizing Interval Cancers

Tumors that are not detected by screening tests are known as interval cancers and are diagnosed clinically after a negative result in the screening episode but before the next screening invitation. Clinical characteristics associated with interval colorectal cancers have been studied, but few molecular data are available that describe interval colorectal cancers. A better understanding of the clinical and biological characteristics associated with interval colorectal cancer may provide new insights into how to prevent this disease more effectively. This review aimed to summarize the current literature concerning interval colorectal cancer and its epidemiological, clinical, and molecular features.