Aims
Optical diagnosis of deep submucosal invasion in early rectal cancer (ERC) remains suboptimal, leading to both undertreatment (endoscopic submucosal dissection for deeply invasive disease) and overtreatment (advanced techniques or surgery for superficial lesions). This study evaluated a diagnostic-therapeutic algorithm (PRIME) using deep-margin optical diagnosis (DMOD) to guide selection of the endoscopic resection technique for ERC.1,2
Methods
We performed an interim analysis of prospective data from consecutive rectal lesions at risk of submucosal invasion at a tertiary centre (August 2023-October 2025). An algorithm incorporating DMOD with muscle-retracting sign (MRS) assessment followed by dissection plane selection: endoscopic submucosal dissection (ESD; MRS-negative), endoscopic intermuscular dissection/knife-assisted or device-assisted full-thickness resection (EID/kFTR/FTRD; MRS-positive).
Results
47 lesions were included (44.7% adenocarcinomas). DMOD was feasible in all cases, with MRS detected in 34.0% (16/47) of the lesions. The technical success rate of endoscopic resection was 97.9% (46/47), with ESD performed in 30 lesions (63.8%), EID in 10 (21.3%), kFTR in 5 (10.6%), and FTRD in 1 (2.1%). En bloc, R0 resection, and R0 vertical margin rates were 100% (46/46), 93.5% (43/46), and 97.8% (45/46), respectively. Adverse events occurred in 10.6% (5/47) of patients (AGREE grade I-IIIa). Rectal preservation rate was 91.5% (43/47). Primary outcomes did not differ significantly between MRS-positive and MRS-negative lesions (all p>0.05).
|
|
Non-invasive and T1sm1 n=32 |
T1 sm2-3 n=11 |
T2 n=4 |
|
Technical success, n (%) |
32 (100) |
11 (100) |
3 (75.0) |
|
En-bloc*, n (%) |
30 (100) |
11 (100) |
3 (100) |
|
R0*, n (%) |
30 (93.8) |
11 (100) |
2 (66.7) |
|
R0 vertical margin*, n (%) |
32 (100) |
11 (100) |
2 (66.7) |
|
Adverse events, n (%) |
3 (9.4) |
1 (9.1) |
1 (25.0) |
|
Muscle-retracting sign, n (%) |
4 (12.5) |
8 (72.7) |
4 (100) |
|
Histological risk factors, n (%) -No risk factors
|
31 (96.9) 1 (3.1)
0 (0)
0 (0) |
4 (36.4) 7 (63.6)
3 (27.3)
1 (9.1) |
1 (33.3) 2 (66.7)
1 (33.3)
1 (33.3) |
Table 1. Technical and histological outcomes of endoscopic resetion.
Conclusions
Deep margin optical diagnosis reliably guided rectal endoscopic resection, achieving excellent oncologic radicality and safety in both MRS-positive and MRS-negative lesions. The PRIME algorithm prevented unnecessary escalation in superficial disease while avoiding undertreatment of deeply invasive cancers.