Technical and oncological outcomes of endoscopic resection of T1 colorectal cancer according to optical diagnosis classification

Aims Optical diagnosis attempts to guide the endoscopist in making a treatment choice, however, selecting lesions with possible covert cancer (CONECCT IIA lesions: JNET IIA, no macronodule, no depressed area), high-risk lesions (CONECCT IIC lesions: JNET IIB or macronodule or depressed area) or overt submucosal invasive carcinoma (SMIC) (CONECCT III=JNET III area) remains challenging. We aim to describe the endoscopic and oncologic outcomes of endoscopically removed T1-colorectal cancers (T1-CRC), according to their pre-resection classification by optical diagnosis.

Methods Multicenter prospective cohort study in 13 centers. Procedural and oncological outcomes were analyzed using univariate analysis [1].

Results 7495 colorectal ESDs were included from 09/2019 to 09/2024, of which 10.4% were T1-CRC. Median lesion size 50mm [35-65], with rectal localization in 35.3% and right colon in 37.9%. Lesions were classified as CONECCT IIA in 30.2%, CONECCT IIC in 64.2% and CONECCT III in 5.6%. En-bloc, R0 and curative resection rates were 96.3%, 88.1% and 81.4%, with significant decreasing trends as the CONECCT classification advanced (97.3%; 91.9%; 90.7% in CONECCT IIA, 96.3%; 87.6%; 80.6% in CONECCT IIC and 93.2%; 74.2%; 32.0% in CONECCT III, respectively; p<0.001). The prevalence of T1-CRC differed significantly with 2.3% in for lesions classified as CONECCT IIA, 10.8% in CONECCT IIC and 49.6% in CONECCT III. For T1-CRCs, en-bloc, R0 and curative resection rates were 96.7%, 74.9% and 23.6% respectively, with a significant decreasing trend regarding curative resection rates as the CONECCT classification increased (25.5% CONECCT IIA, 26.5% CONECCT IIC and 13.9% CONECCT III; p=0.002). Vertical margins were free in 80.3%. Overall median depth of SMIC was 1500µm [750-2560], measuring 1426µm in CONECCT IIA, 1840µm in CONECCT IIC and 2744µm in CONECCT III (p<0.001), corresponding to deep SMIC in 46.8% in CONECCT IIA, 62.2% CONECCT IIC and 77.1% CONECCT III (p<0.001). Lympho-vascular invasion and tumor budding were more often present in CONECCT III with 30.0% and 34.3% respectively (vs 23.9%; 23.9% in CONECCT IIA and 16.4%; 20.6% in CONECCT IIC; p=0.002). Poor differentiation was reported in 5.3% with no significant difference between classification categories. Finally, a bidirectional trend was observed in the number of prognostic risk factors per lesion: no high-risk factors in 34.0% of CONECCT IIA, 29.5% in CONECCT IIC and 18.6% in CONECCT III, versus 3 high-risk factors in 4.3% in CONECCT IIA, 7.0% in CONECCT IIC and 11.2% in CONECCT III (p=0.049).

Conclusions Endoscopic resection of T1-CRC demonstrates high en-bloc and R0 resection rates. However, curative outcomes and oncologic features worsen significantly with the presence of risky optical diagnostic criteria, highlighting the importance of adequate optical diagnosis and considering intramuscular resection techniques for advanced lesions, balancing over- and undertreatment as nearly 50% of CONECCT III lesions were T1-CRC.

Publication History

Article published online:
27 March 2025

• References

• 1 Brule C, Pioche M, Jacques J. et al. The COlorectal NEoplasia Endoscopic Classification to Choose the Treatment classification for identification of large laterally spreading lesions lacking submucosal carcinomas: A prospective study of 663 lesions. United European Gastroenterol J 2022; 10: 80-92