The CRA is a precancerous lesion of CRC, since most of the CRCs develop from CRAs through adenoma-carcinoma pathway. Without timely intervention, precancerous lesions will progress to CRC within 10 to 15 years13. Notably, if the lesions are detected in the early stages of CRC and treated timely, the 5-year survival rate of these patients can reach as high as 90%14. By contrast, if the lesions are detected in the late stages of CRC, the 5-year survival rate will be reduced to less than 10%. Colon endoscopy can directly observe intestinal lesions, which is irreplaceable in the examination of intestinal diseases, especially CRC. To improve the detection rate of precancerous lesions and early-stage CRC, assistive techniques have been introduced to clinical practice, such as chromoendoscopy, magnifying endoscopy, fluorescence endoscopy, confocal laser endoscopy, and electronic staining endoscopy. However, the process of chromoendoscopy is complicated, time-consuming, labor-intensive, and requiring magnification endoscopes. In addition, fluorescence endoscopy and confocal laser endoscopy are expensive. These disadvantages limit the application of the above techniques. Moreover, in clinical practice, the experience and the degree of image interpretation can be varied greatly between endoscopists, which results in different judgments being made for the same lesion, and thus a decrease in the accuracy of colonoscopy. To solve this problem, many endoscopists with extensive experience have defined and standardized the characteristics of CRTs, and several staging systems have been established and promoted, in an attempt to improve the diagnostic accuracy and to reduce the possibility of missed diagnoses. With the advent of magnifying endoscopy, the resolution of imaging has been substantially improved. Now endoscopists can clearly observe the morphology of glandular duct openings and microvasculature on the mucosal surface of CRTs. Kudo’s pit pattern classification15 under magnifying chromoendoscopy was proposed in 1994. Later on, microvessel pattern under magnifying NBI was proposed by Sano et al. in 200616. These staging systems have been highly effective in predicting the histology of CRTs. Subsequently, JNET typing17, Hiroshima typing18, and Jikei typing19 emerged based on mucosal microvascular morphology and surface structure. These typing systems have better performance in differentiating colorectal neoplastic and non-neoplastic lesions by combining the endoscopic features of lesions. Accordingly, the accuracy of differentiating benign from malignant lesions can be improved by providing appropriate training to primary endoscopists. However, the above typing systems require time-consuming, labor-intensive, and magnification endoscopes. Unfortunately, magnification endoscopes are not widely applied in the majority of primary-level hospitals, and a LEE lacks experience in operating NBI + ME. These conditions limit the promotion of staging systems such as Kudo’ pit pattern classification, NICE, and JNET in primary-level hospitals. Therefore, in this study, we have established an online calculator to predict the pathological nature of CRTs based on white-light endoscopy. The model consists of five variables: location of the lesion, size of the lesion, acanthosis, depression, and an uneven surface. The AUC of the scoring system in our modeling cohort was 0.906 (> 0.80), indicating a good degree of differentiation. Based on the Hosmer-Lemeshow goodness-of-fit test (p = 0.225, > 0.1), our prediction model has value for risk-stratification among patients with CRTs of unknown nature, which can provide a preliminary basis for the differential diagnosis of CRT. External verification identified significant improvement in the sensitivity and specificity in the post-training test compared with the pre-training test, especially in the LEEs. Thus, this calculator may be applicable in primary-level hospitals. Our model and its scoring system may have good clinical credibility. Firstly, the methods used for establishing and verifying the models are widely accepted, with external validation among endoscopists with different levels of experience. Secondly, all of the potential predictors were included, and there were no obvious missing items. Thirdly, five variables (location, size, acanthosis, depression, and uneven surface) associated with CRC were obtained by logistic regression models.
The incidence of the left-sided CRC (LCRC) has been higher than that of the right-sided CRC (RCRC). The American Cancer Society confirms a higher proportion of LCRC (51%) than RCRC (42%) in the US20. The patients with RCRC present with more advanced tumor stages than those with LCRC21. Furthermore, higher TNM stages, larger tumors, increased frequency of vascular invasion, mucinous type, high grade and invasive tumor border were more common in RCRC, whereas annular and polypoid tumors were more common in LCRC21,22. In our study, more patients were diagnosed with LCRC than RCRC, which was similar to previous studies.
The CRC is originated from a CRA, which slowly increases in size, followed by dysplasia and malignant transformation23. The size of a CRA is predictive for CRC diagnosis, which underscores the significance of this factor, especially considering its association to a less favorable histology and increased long-term risk of CRC24. The 10 mm cut-off represents a critical factor, since a small percentage of larger polyps contain cancerous cells25,26. Of the 530 lesions with CRTs, 243 were diagnosed as ECRC. The mean size of the lesions was 19.28 ± 11.36 mm, of which 89.7% were ≥ 10 mm, consistent with previous studies.
It was reported that demarcated depression, fullness, and stalk swelling were typical findings of ECRC. Notably, 2.0% of the tumors were carcinoma, especially for depressed tumors, which had a significantly higher frequency of carcinoma and submucosal invasion regardless of tumor size27. The Japanese Guideline for CRC has listed the following endoscopic findings as diagnostic indicators of SM-Ca: expansive appearance, erosion/ulceration, fold convergence, and deformation/stiffness28. In univariate models, most lesions of ECRC had the following characteristics based on WLI: hyperemia, erosion, acanthosis, lobulation, depression, expansive (sun-burst) appearance, larger nodules, and an uneven surface. In multivariate models, five independent risk factors: size, location, acanthosis, depression, and an uneven surface were predictive indicators of ECRC. Thus, a simple online calculator to predict the pathological nature of CRTs based on WLI was established, with an AUC value of 90.6% and high diagnostic specificity and accuracy. Internal and external validation of this model indicated good consistency of CRC risk with postoperative pathology, and good agreement in application between endoscopists with various levels of experiences.
In conclusion, we present a novel online calculator to predict the pathological nature of CRTs. This calculator may play a practical and important role in reducing the cost and duration of colonoscopy. However, this was a single-center study, further high-quality, multi-center clinical studies should be conducted to access the stability and generalizability of this scoring system.