Rethinking treatment for non-metastatic deficient mismatch repair colorectal and small bowel cancers

Table 2 Baseline imaging, endoscopic, and histopathological findings

	CT/MRI	PET/CT	Colonoscopy	Biopsy	IHC
P1	Concentric mural thickening with ulceration and locoregional involvement	Increased metabolic activity	-	-	-
P2	No histopathological findings	Focal hypermetabolic deposit near the hepatic flexure of the colon	Flat elevated lesion with central ulceration, irregular morphology, and a disorganized glandular pattern	ADC	dMMR phenotype (loss of MLH1 and PMS2 expression)
P3	Locally advanced colon cancer, with a necrotic lymph node mass adjacent to the ileocolic region and infiltration into the abdominal wall musculature	-	A mass at the hepatic flexure with extensive, deep ulceration	Poorly differentiated ADC	dMMR phenotype (loss of MLH1 and PMS2 expression) BRAF V600E mutation
P4	Circumferential wall thickening involving the cecum and ascending colon up to the hepatic flexure, with extension into the pericolic fat and ileocolic lymphadenopathy	-	Extensive ulcerated mass from the cecum to the hepatic flexure, involving the ileocecal valve and approximately 75% of the circumference	Poorly differentiated ADC	dMMR (loss of PMS2 expression) BRAF V600E mutation
P5	Wall thickening of the cecum with ileocolic lymphadenopathy	-	Nodular mass at the ileocecal valve involving approximately 75% of the circumference	Moderately differentiated ADC	dMMR (loss of MSH2 and MSH6 expression)
P6	Tumor located 9 cm from the anal verge, staged as cT3bN1b, with EMVI and a threatened CRM (< 1 mm)	Rectal mural thickening with regional lymphadenopathy and no other areas of uptake	Ulcerated lesion extending from 7 to 12 cm from the anal verge	ADC	dMMR (loss MSH6 expression)
P7	Lower rectal cancer staged as cT3b cN1a	-	Ulcerated, eroded tumor located 3-4 cm from the anal verge, involving approximately 50% of the circumference without stenosis	ADC	After CRT and first consolidation CT: DMMR phenotype (loss of PMS2 expression)
P8	Tumor staged as T3bcN2b, located 6 cm from the anal verge, with EMVI positive, threatened CRM < 2 mm, and no lateral lymph nodes	Rectal tumor with no other findings	Stenosing rectal tumor located 9 cm from the anal verge	ADC	After CRT: DMMR (MSH2-, MSH6-)

EMVI: Extramural vascular invasion; CRM: Circumferential resection margin; CT: Computed tomography; MRI: Magnetic resonance imaging; PET/CT: Positron emission tomography/computed tomography; IHC: Immunohistochemical; ADC: Adenocarcinoma; CRT: Chemoradiotherapy; dMMR: Deficient mismatch repair.