Abstract
Background
It is uncertain whether underwater endoscopic mucosal resection (UEMR) enables resection
of the submucosal tissue with sufficient margins for T1 colorectal cancer (CRC) because
UEMR forgoes submucosal injection. Therefore, we developed a novel “underwater injection
EMR” (UIEMR) method that combines submucosal injection with UEMR to obtain an adequate
vertical margin.
Methods
We retrospectively analyzed procedure-related outcomes of 135 consecutive lesions
from patients who underwent UIEMR for ≥10-mm nonpedunculated colorectal polyps (median
size 15 mm). The outcomes included the en bloc, R0, RX, and R1 resection rates, and
adverse events. Additionally, the vertical margin distance of seven T1 CRCs was evaluated.
Results
En bloc resection was achieved in 127 lesions (94.1%). R0 and RX resections were observed
in 92 (68.1%) and 42 lesions (31.1%), respectively, while R1 resection was seen in
only one lesion (0.7%). There were two cases with adverse events (1.5%), both delayed
bleeding. In T1 CRCs, all seven cases had free vertical margins, and the median vertical
margin distance was 1140 µm (range 731–1570 µm).
Conclusions
UIEMR safely demonstrated high success rates for en bloc resection, and potentially
ensures a sufficient vertical margin. This technique might be an option, particularly
for relatively small lesions concerning for T1 CRC, and deserves further study.
