MEDIUM-TERM ONCOLOGICAL OUTCOMES FOLLOWING ENDOSCOPIC FULL-THICKNESS RESECTION FOR T1 COLORECTAL CANCER: RESULTS FROM THE DUTCH PROSPECTIVE COLORECTAL EFTR REGISTRY

Endoscopic full thickness resection (eFTR) is increasingly used as a minimally invasive diagnostic and potential therapeutic approach for smaller (≤2cm) T1 colorectal cancer (CRC). EFTR enables transmural resection, providing optimal histologic risk assessment and complete (R0) resection even in deep submucosal invasive cancer (D-SMIC). However, follow-up (FU) outcomes have not yet been described. This study aims to describe the medium-term oncologic results of eFTR for T1CRC

All consecutive eFTR procedures for suspected T1CRC enrolled in the Dutch prospective eFTR registry from November 2015 to November 2023 were analyzed. Superficial submucosal invasive cancer (S-SMIC) was defined as sm1, D-SMIC as sm2-3. High-risk T1CRC was defined by the presence of lymphovascular invasion, budding grade 2-3, poor differentiation or tumor-positive resection margins (<0.1mm). Deep submucosal invasion was not considered an independent risk factor according to the Dutch CRC guideline. Oncologic surveillance comprised endoscopy with or without imaging, as per guideline and depending on histology. Outcomes included R0 resection rate, cancer recurrence, 3-year disease-free survival (DFS) and 3-year overall survival (OS)

In total, 556 patients with suspected T1CRC were included (median age 73 years, 58% male, median lesion size 15mm). Histology confirmed pT1 in 333 (60%) patients, including 78 (25%) S-SMIC and 250 (75%) D-SMIC, ≥pT2 in 119 (21%) and non-invasive histology in 104 (19%). R0 resection rates were 94% for S-SMIC and 89% for D-SMIC, with no significant differences for colon vs rectum or lesion size (≤15mm vs 16-20mm). Histopathology revealed risk factors in 140 (42%) T1CRCs, leading to completion surgery (CS) in 77 (55%) patients, with 12 (16%) having residual cancer (2 endoluminal, 10 nodal), all with ≥2 risk factors. At least 1 FU visit was recorded for 235 T1CRCs, with a median FU of 42 months (IQR 34), 2 endoscopies (0-7) and 1 imaging procedure (0-7). The FU cohort was divided into low-risk T1CRC with surveillance (n=122), high-risk T1CRC with surveillance (n=51) and CS (n=62). In the low-risk group, cancer recurred in 2/122 (2%); 1/44 (2%) S-SMIC with distant metastases and 1/78 (1%) D-SMIC with a positive lymph node treated with salvage surgery. In the high-risk group, cancer recurred in 3/51 (6%); 1 local lymph node treated with salvage surgery and 2 distant metastases. In the CS group, distant metastases occurred in 4/62 (7%), all without curative options. 3-year DFS and 3-year OS were 98% and 91% for the low-risk group, 95% and 83% for the high-risk group, and 94% and 97% for the CS group

EFTR is an efficient first-line treatment for T1CRC ≤2cm, demonstrating high R0 resection rates for both S-SMIC and D-SMIC. Furthermore, eFTR allows organ preservation in a large proportion of patients, with low cancer recurrence rates over a median FU of 42 months