New and Recurrent Colorectal Cancers After Resection: a Systematic Review and Meta-analysis of Endoscopic Surveillance Studies

Abstract

Background & Aims: Outcomes of endoscopic surveillance following surgery for colorectal cancer (CRC) vary with the incidence and timing of CRC detection, at anastomoses or nonanastomoses in the colorectum. We performed a systematic review and meta-analysis to evaluate the incidence of CRCs identified during surveillance colonoscopies of patients who have already undergone surgery for this cancer. Methods: We searched PubMed, EMBASE, SCOPUS, and the Cochrane Central Register of Clinical Trials through January 1, 2018 to identify studies investigating rates of CRCs at anastomoses or other locations in the colorectum after curative surgery for primary CRC. We collected data from published randomized controlled, prospective, and retrospective cohort studies. Data were analyzed by multivariate meta-analytic models. Results: From 2373 citations, we selected 27 studies with data on 15,803 index CRCs for analysis (89% of patients with stage 1-3 CRC). Overall, 296 CRCs at non-anastomotic locations were reported over time periods of more than 16 years (cumulative incidence, 2.2% of CRCs; 95% CI, 1.8%-2.9%). The risk of CRC at a non-anastomotic location was significantly reduced more than 36 months after resection compared with before this timepoint (odds ratio for non-anastomotic CRCs at 36-48 months vs 6-12 months after surgery, 0.61; 95% CI, 0.37-0.98; P=.031); 53.7% of all non-anastomotic CRCs were detected within 36 months of surgery. One hundred fifty-eight CRCs were detected at anastomoses (cumulative incidence of 2.7%; 95% CI, 1.9%-3.9%). The risk of CRCs at anastomoses was significantly lower 24 months after resection than before (odds ratio for CRCs at anastomoses at 25-36 months after surgery vs 6-12 months, 0.56; 95% CI, 0.32-0.98; P=.036); 90.8% of all CRCs at anastomoses were detected within 36 months of surgery. Conclusions: After surgery for CRC, the highest risk of CRCs at anastomoses and at other locations in the colorectum is highest during 36 months after surgery-risk decreases thereafter. Patients who have undergone CRC resection should be evaluated by colonoscopy more closely during this time period. Longer intervals may be considered thereafter.

British Society of Gastroenterology/Association of Coloproctology of Great Britain and Ireland/Public Health England post-polypectomy and post-colorectal cancer resection surveillance guidelines

“…Three studies presented evidence per age group relative to the younger age group. Martinez et al 12 reported statistically significant increased risks for AN across three age groups (61–71; 80+years) compared with the younger age group (50–59 years), with incidence of AA at first surveillance as 12.2%, 14.5%, and 17.7%, respectively. Furthermore, Martinez et al also presented evidence on the younger than 40 age group, and the 40–49 age group relative to the 50–59 age group.…”

“…The presence of synchronous CRC was the only significant risk factor for developing metachronous CRC (RR 13.9, 95% CI 4.7 to 41.0). However, a recent systematic review and meta-analysis shows that the absolute risk is substantially lower than 1%, ranging between 0.63% and 0.74% in the first 3 years of follow-up, further dropping to <0.5% after 36 months 66…”

“…The risk of metachronous cancer development is highest in the first 3 years after diagnosis of CRC 66 70. This increased risk is particularly common in older studies or in those where perioperative colonoscopy was not systematically performed 70.…”

COVID-19 and endoscopy: implications for healthcare and digestive cancer screening

“…In a large retrospective cohort study from the UK evaluating the effectiveness of post-polypectomy colonoscopy surveillance on incident colorectal cancer, Cross et al reported that, compared with the general population, CRC incidence without surveillance was similar among low-risk and intermediate-risk groups, but significantly higher in the high-risk group. However, a possible exception is the need for early colonoscopy surveillance following complex polyp resection (for example, endoscopic mucosal resection or endoscopic submucosal dissection) or following endoscopic management of early gastric cancer because these patients have been shown to be at high-risk for residual or recurrent disease 9,10 . Delays for endoscopic surveillance are now common owing to endoscopy units temporarily suspending such procedures, a lack of endoscopy personnel to perform these procedures as many have been assigned to other medical wards to care for patients with COVID-19 or are sick or isolating themselves, or because patients decide to stay away from hospitals.…”

Can Colonoscopy Sow the Seeds of Colorectal Cancer?

“…5 These mechanisms apply both to cancers occurring after a clear colonoscopy, and to metachronous cancers occurring after a colorectal cancer is resected, which occurs after up to 3% of surgical resections. 6,7 In this issue of Gastroenterology, Backes et al in a proof-of-principle study suggest a fifth mechanism for development of colorectal cancer after colonoscopy: iatrogenic mechanical tumor seeding via the biopsy channel of the colonoscope (Figure 1). 8 Causality of seeding after biopsy is difficult to prove.…”