Prevalence and predictors of interval colorectal cancers in Medicare beneficiaries

Abstract

Background Following a colonoscopy that is negative for cancer, a subset of patients may be diagnosed with colorectal cancer, also termed interval cancer. The frequency and predictors have not been well studied in a population-based U.S. cohort. Methods Using the linked SEER-Medicare database, we identified 57,839 patients aged ≥ 69 with colorectal cancer diagnosed between 1994 and 2005 and who underwent colonoscopy within 6 months of cancer diagnosis. Colonoscopy performed between 36 to 6 months prior to cancer diagnosis was a proxy for interval cancer. Results Using the case definition, 7.2% of patients developed interval cancers. Factors associated with interval cancers included proximal tumor location (distal colon multivariable OR 0.42, 95% CI 0.390–0.46, rectum OR 0.47, 95% CI 0.42–0.53), increased comorbidity (OR 1.89 95% CI 1.68 2.14 for 3 or more comorbidities), a previous diagnosis of diverticulosis (OR 6.00 95% CI 5.57–6.46), and prior polypectomy (OR 1.74, 95% CI 1.62–1.87). Risk factors at the endoscopist level included a lower polypectomy rate (OR 0.70, 95% CI 0.63–0.78 for the highest quartile), higher colonoscopy volume (OR 1.27, 95% CI 1.13–1.43) and specialty other than gastroenterology (colorectal surgery OR 1.45, 95% CI 1.16–1.83; general surgery OR 1.42, 95% CI 1.24–1.62; internal medicine OR 1.38, 95% CI 1.17–1.63, family practice OR 1.16, 95% CI 1.00–1.35). Conclusions A significant proportion of patients develop interval colorectal cancer, particularly in the proximal colon. Contributing factors likely include both procedural and biologic factors, and emphasize the importance of meticulous examination of the mucosa.

Adenoma Detection Rate and Risk of Colorectal Cancer and Death

“…Previous studies have focused primarily on cancers occurring within 3 to 5 years after the colonoscopic examination; rapidly progressing adenomas or cancers that were present but not detected at the time of colonoscopy would presumably account for these interval cancers. 15,21,29,30,[33][34][35][36][37][38][39][40][41] The number of cancers detected in this study is similar to or lower than the numbers observed in other studies (which often evaluated cancers over a shorter period). 29,30 Interval cancers accounted for only 8.2% of all colorectal cancers detected in our study cohort, and the absolute risk of an interval cancer was relatively low (9.8 interval cancers per 10,000 person-years of follow-up in quintile 1 of adenoma detection rates and 4.8 interval cancers per 10,000 person-years of follow-up in quintile 5).…”

Intraprocedural Cleansing for Screening Colonoscopy: Avoiding Brownouts

“…This study reinforces current concerns regarding postscreening colonoscopy interval cancers by confirming that NP-CRNs can be easily missed as a result of inadequate colon preparation, supported by the observation that interval cancers cluster in the right colon (cecum and ascending colon) [6], traditionally recognized as the colonic segments most difficult to prepare [5]. Interval cancers are associated with colonoscopists with low ADRs [7]; the desirability of achieving high ADR is emphasized by the observation that a 1 % increase in ADR reduces the overall risk of interval cancer by 3 % and fatal cancers by 5 % [8].…”

Simple Clinical Risk Score Identifies Patients with Serrated Polyps in Routine Practice

“…As colonoscopy with the removal of precancerous lesions is considered the gold standard modality in the prevention of colorectal cancer (1), concerns were raised by studies showing limited effectiveness of colonoscopy in the proximal colon (2)(3)(4). The serrated neoplastic pathway may contribute to the occurrence of some postcolonoscopy cancers, as some precursor lesions, especially sessile serrated adenomas/polyps (SSA/P), are easily overlooked during colonoscopy (5,6) and are more challenging to remove endoscopically (7).…”