Incomplete screening flexible sigmoidoscopy associated with female sex, age, and increased risk of colorectal cancer

Abstract

Background: Several previous studies have found that females and older individuals are at greater risk of having incomplete flexible sigmoidoscopy. However, no prior study has reported the subsequent risk of colorectal cancer (CRC) following incomplete sigmoidoscopy. Methods: Using data from 55 791 individuals screened as part of the Colon Cancer Prevention (CoCaP) programme of Kaiser Permanente of Northern California, we evaluated the likelihood of having an inadequate (,40 cm) examination by age and sex, and estimated the risk of distal CRC according to depth of sigmoidoscope insertion at the baseline screening examination. Multivariate estimation of risks was performed using Poisson regression. Results: Older individuals were at a much greater risk of having an inadequate examination (relative risk (RR) for age 80+ years compared with 50-59 years 2.6 (95% confidence interval (CI) 2.3-3.0)), as were females (RR 2.3 (95% CI 2.2-2.5)); these associations were attenuated but remained strong if Poisson models were further adjusted for examination limitations (pain, stool, and angulation). There was an approximate threefold increase in the risk of distal CRC if the baseline sigmoidoscopy did not reach a depth of at least 40 cm; a smaller increase in risk was observed for examinations that reached 40-59 cm. Conclusions: Older individuals and women are at an increased risk of having inadequate sigmoidoscopy. Because inadequate sigmoidoscopy results in an increased risk of subsequent CRC, physicians should consider steps to maximise the depth of insertion of the sigmoidoscope or, failing this, should consider an alternative screening test.

Ten-year incidence of colorectal cancer following a negative screening sigmoidoscopy: an update from the Colorectal Cancer Prevention (CoCaP) programme

“…For example, our data suggest that the duration of low risk of distal CRC after a negative sigmoidoscopy is longer among younger individuals. Also, there is a growing body of research implicating various endoscopy quality indicators, such as depth of insertion,21 adenoma detection rate38 39 and endoscopist specialty (which may serve as a proxy for quantity/quality of endoscopist training),32 38 40–42 with the occurrence of CRC after endoscopy. Therefore, the absolute risk and patterns of CRC incidence postendoscopy could differ in different populations and healthcare settings.…”

“…Using the CoCaP database, we previously defined a cohort of 72 483 KPNC members who had a screening sigmoidoscopy negative for both polyps and cancer between 1994 and 1996; approximately 80% of the total number of those screened were included based on their negative exam 21. Cohort inclusion and exclusion criteria, and cancer incidence during the first 5 years after negative sigmoidoscopy have previously been described 20.…”

Concerns and challenges in flexible sigmoidoscopy screening

“…Furthermore, those with inadequate FS (particularly if due to discomfort) were more likely to have inadequate FS at repeat examination (OR: 6.24; 95% CI: 5.77–6.75), underscoring the importance of offering sedation to the patient or switching to another screening modality. Inadequate FS has also been associated with subsequent CRC [63]. It is important for patients and providers to strive to ensure an adequate FS at the first screening attempt.…”

Factors associated with inadequate colorectal cancer screening with flexible sigmoidoscopy

“…Furthermore, inadequate FSG has been associated with subsequent colorectal cancer (3, 4). Previous studies, largely single institution experience with relatively small numbers of patients, have suggested that older individuals and women are more likely to have inadequate FSG, but there is limited information on other factors that may be associated with inadequate FSG (5, 6).…”