From surface to depth: Combining white-light and ultrasound endoscopy to predict complete response in rectal cancer

Figure 1 Representative white light endoscopy and endoscopic ultrasound images at response assessment. A: White light endoscopy (WLE) image displaying endoscopic CR (eCR) morphology, characterized by a flat white scar with telangiectasia, no ulceration, and no nodularity; B: WLE image displaying near-eCR morphology, mild mucosal irregularity and superficial ulceration without obvious tumor mass; C: WLE image displaying non-eCR morphology, with visible exophytic or ulcerative tumor lesion at the original tumor site; D: Endoscopic ultrasound (EUS) image displaying completely restored wall layers, showing clear, distinct, and continuous anatomical layers; E: EUS image displaying partially restored layers, demonstrating some focal structural disruption or thickening but with visible layer structures; F: EUS image displaying mass echo pattern, presenting as a distinct hypoechoic lesion disrupting the normal wall layers.

Figure 2 Flowchart of patient selection and study protocol. CR: Complete response; pCR: Pathological complete response; LARC: Locally advanced rectal cancer; nCRT: Neoadjuvant chemoradiotherapy.

Figure 3 Receiver operating characteristic curves for predicting complete response by two independent endoscopists (R1, R2) and consensus strategy by joint discussion (R1 + R2) (n = 145). A: White light endoscopy; B: Endoscopic ultrasound. AUC: Area under the curve; CI: Confidence interval.

Figure 4 Changes in maximum tumor thickness measured by endoscopic ultrasound. Data are presented as the median (range) in millimeters (mm) (n = 73). A: Comparison of tumor thickness at baseline (EUS1) and post-treatment (EUS2); B: Comparison of post-treatment tumor thickness (EUS2) between the complete response (CR) and non-CR groups. CR: Complete response; EUS: Endoscopic ultrasound.

Figure 5 Development and validation of the predictive nomogram for complete response. A: Nomogram incorporating clinical location, whitelight endoscopy, and endoscopic ultrasound feature to estimate the individualized probability of complete response; B: Calibration curve demonstrating excellent agreement between the nomogram-predicted and actual observed probabilities; C: Decision curve analysis showing that the nomogram provides a superior clinical net benefit across a wide range of threshold probabilities compared to default strategies; D: Receiver operating characteristic curve for the nomogram predicting complete response. CR: Complete response; WLE: White light endoscopy; EUS: Endoscopic ultrasound; H-L: Hosmer-Lemeshow; AUC: Area under the curve; CI: Confidence interval.