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case_images: Electron colorectoscopic and Rectal high-resolution MRI presentation before treatment (A-C) Irregular mass grown in the lumen of the rectum with ulcerated surface adjacent to the anal verge. (D-F) Pre-treatment rectal MRI evaluation: low, about 37 mm from the anal verge, T3cA2N2Mx, CRM (-), EMVI (-).
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case_images: Electronic colonoscopy revealed a circumferential ulcerated neoplasm near the rectum, and a biopsy confirmed the diagnosis of rectal adenocarcinoma (Figure 1A-C). More than four abnormal lymph nodes with altered signals were detected in the mesorectal area, the largest having a short diameter of about 8 mm (Figure 1D-F).
case_images: Schematic of Target Delineation (A-D) Gross Tumor Volume Schematic Red outlining: Gross Tumor Volume Yellow outlining: Organ at risk.
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case_images: The target area for radiotherapy included the internal iliac lymph node drainage area, occlusive lymph node drainage area, presacral area, and rectal mesenteric lymphatic drainage area, while sparing critical organs such as the bladder, small intestine, and femoral heads (Figure 2A-D).
case_images: Schematic of Radiotherapy Planning: (A-D) Isodose curve schematic. (E) Dose-volume histogram (DVH) schematic.
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case_images: The dose distribution was uniform, with no evidence of hot or cold spots (Figure 3A-E).
case_images: Electron colorectoscopic and Rectal high-resolution MRI presentation after chemoradiotherapy (A-C) Ulcerative lesion of the circumferential lumen formed about 4 cm to 7 cm from the anal verge, with a whitish mossy underside and a congested and reddened surrounding mucosa. (D-F) Rectal high-resolution MRI scan review after concurrent chemoradiotherapy showed: the lesion was significantly shrunken.
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case_images: Following completion of chemoradiotherapy, rectal MRI scans indicated significant reduction of the lesion (Figure 4D-F). Electronic colonoscopy revealed a circumferential ulcerative lesion occupying approximately 2/5 of the intestinal lumen, located 4-7 cm from the anal verge (Figure 4A-C).
case_images: Electron colorectoscopic and Rectal high-resolution MRI presentation after 6 cycles of chemotherapy (A-C) Scarring of the mucosa of the distal rectum with ulcer formation. Capillaries dilated in the mucosa of the rectum and distal sigmoid colon. (D-F) After 6 cycles of consolidation chemotherapy, the rectal high-resolution MRI showed: no obvious thickening and abnormal signal in the intestinal lumen.
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case_images: MRI scans showed no significant thickening or abnormal signal in the rectal wall (Figure 5D-F), and electronic colonoscopy revealed that the ulceration was replaced by inflammatory granulation tissue, with no residual tumor lesions (Figure 5A-C). Multidisciplinary team (MDT) consultation classified the treatment response as a near clinical complete response (near-cCR) according to the RECIST 1.1 criteria.