Interval cancers after colonoscopy—insights and recommendations

Abstract

Several studies have raised warnings about the limited effectiveness of colonoscopy for the prevention of colorectal cancer (CRC), especially of the proximal colon. Two major categories of factors might be responsible for the development of interval cancers, namely technical, endoscopist-dependent factors and biological characteristics of the cancer that lead to more rapid tumour progression. Recognition of endoscopist-dependent factors is critical, as these factors are probably amenable to correction through improved awareness and education of endoscopists, using quality metrics (such as adenoma detection rates and cecal intubation rates) for objective evaluation and feedback. In this article, the current literature regarding the incidence of, and potential explanations for, interval CRCs is outlined. Although there is probably an interaction between technical and biology-related factors--and an attempt to dissect the biology from the technology might be fraught with difficulties--a structured analysis of individual cases of interval cancer might help in the continuous monitoring of the quality of colonoscopy, and ultimately might reduce the number of interval CRCs.

Colonoscopy reduced distal colorectal cancer risk and excess cancer risk associated with family history

“…In addition, tumors of the proximal colon more often develop from serrated adenomas which often harbor-specific features, such as microsatellite instability, BRAF mutations, or high gene methylation as compared with distal tumors. It has been suggested that these features could be associated with fast tumor progression [26]. Therefore, the adenoma-carcinoma process could be faster in proximal than in distal tumors.…”

Pólipos serrados y síndrome de poliposis serrada

“…El CCR de intervalo comparte las mismas características clínicas y moleculares que los pó lipos serrados, localizació n proximal y alteraciones moleculares propias de la vía serrada (mutació n en el gen BRAF y CIMP), por lo que se ha sugerido que una de las principales causas del CCR de intervalo son los pó lipos serrados inadvertidos 41 .…”

Post-colonoscopy colorectal cancers in average-risk Korean subjects with a normal initial colonoscopy

“…In a pooled analysis of eight large North American prospective studies that involved 9167 participants with a median follow-up of 47.2 months, the incidence of interval cancer was low (0.6%, or 1.71 per 1000 person-years of follow-up) (24). However, assuming that the incidence of new cases of CRC is approximately 1,000,000 per year worldwide and considering that 1 of 30 diagnosed CRCs is an interval cancer, the occurrence of >30,000 interval cancers might be annually expected (9). In both our study and a prior Japanese multicenter retrospective study (17), the incidences of PCCRC were lower (1.5% and 0.55%, respectively) compared with those in Western studies.…”

“…Emerging evidence indicates that the incidence of interval cancers markedly varies, ranging from 1 in 130 to 1 in 1,000 colonoscopies or 1 in 13 to 1 in 45 of all diagnosed CRCs (9). While the term "interval CRC" appears to be suitable for CRCs identified in the interval between screening and surveillance, the term "post-colonoscopy CRC (PCCRC)" describes CRCs found after a colonoscopic examination, regardless of whether the indication for colonoscopy is screening or diagnosis (10).…”