[Colorectal cancer: role of imaging in screening]

Establishment and evaluation of a nomogram predicting risks of missed diagnoses of colorectal polyps

Background

A missed diagnosis of colorectal polyps during colonoscopy may be associated with the occurrence of interval colorectal cancer. The risk factors for a missed diagnosis or a method to predict the risk of a missed diagnosis of colorectal polyps during colonoscopy remain unidentified.

Methods

The clinical data of patients who underwent two colonoscopies within three months at the Affiliated Hospital of North Sichuan Medical College between February 2017 and August 2019 were retrospectively reviewed. Independent risk factors for missed diagnoses were identified, and a nomogram was established to predict the risk of missed diagnoses. The prediction performance of the nomogram was evaluated using C-index and calibration curves, and its clinical application value was assessed using the Youden index and decision curve analysis.

Results

Independent influencing factors for missed diagnoses included age, endoscopist experience, bowel preparation, retroflected view, withdrawal time, number of polyps in the right colon, and number of polyps ≥ 6 mm. The C-index of the nomogram in the training and validation cohorts was 0.763 (95% confidence interval [CI]: 0.724 − 0.807) and 0.726 (95%CI: 0.657 − 0.794), respectively. The optimal cut-off value of the nomogram calculated using the Youden index was 152.2 points. Under the cut-off value, the sensitivity, specificity, positive predictive value, and negative predictive value were 67.1%, 75.7%, 45.8%, and 88.2%, respectively, in the training cohort, and 57.1%, 79.9%, 53.3%, and 82.3%, respectively, in the validation cohort.

Conclusions

The nomogram provides a reference value for clinicians to analyse the risk of a missed diagnosis of colorectal polyps in individuals, identify high-risk groups, and formulate appropriate follow-up strategies.

Value of multi-slice spiral computerized tomography for diagnosis of synchronous colorectal carcinoma: a retrospective study

Objective

To compare the accuracy of multi-slice spiral computerized tomography (MSCT) with colonoscopy for diagnosing synchronous colorectal carcinoma (SCC).

Methods

We retrospectively analyzed all consecutive patients admitted to our institution with colorectal carcinoma between 19 September 2014 and 31 January 2020. Data on SCC patients who had undergone MSCT and colonoscopy were analyzed. Information on tumor location, tumor size, missed diagnosis by MSCT or colonoscopy, T stage, pathological type, and reasons for missed diagnosis was recorded and used to assess the diagnostic accuracies of MSCT and colonoscopy.

Results

Twenty-three cases met the inclusion criteria. MSCT plus colonoscopy had a significantly higher diagnostic accuracy (93.5%) than colonoscopy alone. There were significant differences in missed diagnosis rates of proximal cancer (34.8%) and distal cancer (4.3%) by colonoscopy. For MSCT, the missed diagnosis rate for tumors with a median long diameter of 1.25 cm (interquartile range 0.80, 1.50) was significantly lower than that for larger tumors (long diameter 4.00 cm; 3.00, 6.00).

Conclusions

MSCT is a valuable diagnostic tool for SCC that can effectively minimize the missed diagnosis rate of primary tumors when combined with colonoscopy.

Value of combined detection of IFOBT, tumor markers, and inflammatory markers in predicting occurrence of advanced colorectal adenoma

BACKGROUND

At present, there is a lack of effective, non-invasive screening tests for colorectal precancerous lesions. Identification of high-risk groups and multi-biomarker detection have become the trend of cancer and precancerous lesion screening. Inflammatory markers have been widely used in the diagnosis and prognosis of various tumors, but there are few studies on their diagnostic value in precancerous lesions.

AIM

To explore the predictive value of the general characteristics, neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), CEA, CA199, and immunochemical fecal occult blood testing (IFOBT) in the occurrence of advanced colorectal adenoma.

METHODS

Two hundred and ninety-five cases of advanced colorectal adenomas confirmed by pathology and electronic colonoscopy at our hospital from 2014 to 2018 were retrospectively analyzed, and 448 cases of non-advanced adenomas in the same period were selected as a control group. The general clinical data of the patients, including basic characteristics (gender and age), living habits (smoking and drinking), and past history of disease (hypertension, coronary heart disease, diabetes), history of surgery (history of cholecystectomy or appendectomy), and laboratory examinations (NLR, PLR, CEA, CA199, and IFOBT) were collected. Measurement data were compared using t-test or Mann-Whitney U test, and count data were compared using χ² test. Statistically significant variables were included in binary logistic regression analysis. ROC curve was drawn to evaluate the predictive value of related indexes in the occurrence of advanced colorectal adenoma.

RESULTS

Multivariate logistic regression analysis demonstrated that age (odds ratio [OR] = 1.047, 95% confidence interval [CI]: 1.028-1.066, P = 0.000), smoking (OR = 1.880, 95%CI: 1.250-2.826, P = 0.002), diabetes (OR = 2.073, 95CI%: 1.216-3.535, P=0.007), previous cholecystectomy (OR = 9.206, 95CI%: 2.904-29.181, P = 0.000), IFOBT (OR = 7.681, 95%CI: 4.585-12.869, P = 0.000), CA199 (OR = 1.039, 95%CI: 1.018-1.059, P = 0.000), and NLR (OR = 1.706, 95%CI: 1.388-2.097, P = 0.000) were independent factors for advanced colorectal adenoma. ROC analysis showed that the areas under the ROC curves (AUCs) of IFOBT, CA199, and NLR in predicting advanced colorectal adenoma were 0.644 (95%CI: 0.602-0.686), 0.639 (95%CI: 0.598-0.679), and 0.645 (95%CI: 0.605-0.685), respectively. The optimal cutoff values for NLR and CA199 were 2.04 and 7.87 U/mL, respectively. The sensitivity and specificity of IFOBT, CA199, and NLR in predicting advanced colorectal adenoma were 34.6% and 94.2%, 53.9% and 66.1%, and 50.2% and 71.8%, respectively. The AUC of combination of the three biomarkers for the diagnosis of advanced adenoma was 0.752 (95%CI: 0.716-0.788), with a sensitivity of 52.9%and specificity of 82.8%. In the subgroup analysis, there were significant differences between the IFOBT(+) subgroup and IFOBT(-) subgroups with regard to tumor location (P = 0.048), diameter (P = 0.000), and differentiation(P = 0.000). There were also significant differences between the low NLR (< 2.04) subgroup and high NLR (≥ 2.04) subgroup with regard to gender (P = 0.004), tumor diameter (P = 0.028), and tumor differentiation (P = 0.000).

CONCLUSION

Advanced colorectal adenoma is associated with advanced age, smoking, diabetes, and previous cholecystectomy, and more attention should be paid to populations with these risk factors. IFOBT, NLR, and CA199 have appreciated diagnostic value for advanced colorectal adenoma, with the combination of all three having the highest diagnostic value.