This is the largest prospective study addressing the safety and efficacy of EMR for the treatment of LSTs in a Western cohort. We have shown that EMR can achieve high endoscopic “cure” rates in a selected cohort of lesions that is comparable with the Japanese experience of Tanaka and colleagues,6
Saito and colleagues,8
and Higaki and colleagues.7
These data may change the current management approach of LSTs from that of primary surgical resection to include endoscopic based strategies. The low elevated morphological characteristics of LSTs also makes them ideal candidates for “on table” staging using new technologies such as HMC and HFUS, often not possible in the assessment of sessile and subpedunculated colorectal lesions.18
Our data show a propensity of F-type LSTs for the right colon (77% (20/26)) and also a higher incidence of submucosal invasion (38% (10/26)) compared with G-type lesions (39% (22/56) and 9% (5/56), respectively). Our observations validate Tanaka’s series where there was a higher frequency of submucosal invasion in F-type compared with G-type lesions (p<0.05).6
G-type lesions in our series were also significantly larger than F-type lesions (p<0.01), a finding similar to that of Yoshikane and colleagues,19
Okamoto and colleagues,3
and Saito and colleagues.8
Furthermore, the frequency of invasive carcinoma in G-type LSTs was less than for exophytic lesions of comparable size.20
Fifteen stage T2 carcinomas (invading the muscularis) were diagnosed in our series (five G-type/10 F-type), and were excluded from EMR (18% (15/82) of the cohort). All of these lesions were correctly staged endoscopically using a combination of chromoscopy to accurately delineate morphology, crypt pattern analysis to identify an invasive type V pattern, and localisation of the submucosal layer 3 and muscularis propria using HFUS. Although in this study we correctly predicted 100% of invasive neoplasms by combining these techniques, new technologies such as HMC and HFUS are not available at many centres and carry a significant expense with requirements for further specialised training. However, given this limitation to our study, 13 lesions were diagnosed as stage T2 on the basic chromoscopic criteria of central depression and the non-lifting sign at submucosal injection.21
Therefore, even without HMC and HFUS, 86% (13/15) of T2 lesions would have been correctly anticipated using these basic endoscopic signs.
Although the risk of local nodal metastasis is low (5–10%) for stage T1 G-type and F-type LSTs,10
there remains a risk that endoscopic resection may leave untreated nodal disease in situ. The efficacy of routine preoperative computed tomography (CT) for the preoperative diagnosis of lymph node involvement has however been addressed by McAndrew and Saba.22
In this series of 180 patients undergoing surgery for primary colorectal carcinoma, only 19% of patients with lymph node involvement were correctly staged using CT. Furthermore, the utility of routine preoperative CT scanning in the management of colorectal cancer was shown to be unhelpful by Barton et al
with clinical management decisions being definitively altered in only 19% of patients.23
Isbister and al-Sanea also demonstrated similar data in their prospective analysis of preoperative CT scanning in the assessment of colorectal cancer management.24
In this series, definitive management changes were proposed in only 12% of cases.24
In contrast with preoperative CT imaging, Hunerbein et al
have recently assessed the efficacy of mini probe ultrasonography for the prediction of lymph node metastasis in patients with gastric and colorectal neoplasia.25
Lymph node status was correctly predicted in 82% of cases (sensitivity 61%/specificity 94%).25
Based on mini probe staging criteria, patients with gastric cancer were accurately selected to undergo EMR, laparoscopic resection, or open surgery in 100%, 91%, and 86% of cases, respectively. Furthermore, in patients with colorectal tumours, the treatment decision analysis showed correct stratification in 90% of patients.25
Our study used combination in vivo staging with HFUS and HMCC, which at present appears to be the optimal staging modality to predict local nodal disease compared with CT imaging. Two lesions (one G-LST/one F-LST) were referred for surgical resection in our series due to recurrent disease at six months of follow up. Both lesions demonstrated the non-lifting sign at follow up EMR but had no evidence of local nodal disease at HFUS, confirmed at subsequent laparotomy. Therefore, in clinic practice the risk of local nodal metastases should be discussed with the patient, where the low risk of leaving local lymph nodes in situ can be debated against the overall risk of surgery on consideration of the wider clinical context (that is, patient age and comorbidity). We therefore propose that EMR of LSTs can be practised safely in both the district general and specialised tertiary referral endoscopic units.
Of the 58 lesions undergoing EMR, 10% (6/58) were complicated by bleeding but there were no perforations. These data represent a higher bleed rate compared with Higaki’s series7
(4% (1/23)) but lower than that reported by Tanaka et al
Such data are comparable with those of Walsh and colleagues20
and Bedogni and colleagues26
who reported a bleed frequency (procedural and delayed) of 3–12% for snare resection of giant colorectal polyps. However, all bleeding complications in both of our series and others were managed successfully using endoscopic clipping with no requirement for surgical intervention.
Endoscopic follow up in our study was performed at similar time intervals to Higaki’s series7
(3, 6, 12, and 24 months post index resection) with those in Tanaka’s cohort undergoing a mean follow up of 60.8 (SD 20.1) months.6
Of the 10 recurrent lesions in our series, all were diagnosed at the first six month follow up colonoscopy and all but one were adenomatous lesions accompanying the index lesion. In the single exception, a carcinoma (stage T1) was identified as a flat 3 mm lesion at the resection base of a 20 mm F-type LST with a type IIIs crypt pattern. These data are comparable with those of Tanaka’s series where 83% (5/6) of cases of recurrent disease were diagnosed within six months of the index EMR.6
Only one patient in Tanaka’s cohort developed a recurrent adenoma at 13.5 months post index resection of a 20 mm G-type ascending colonic lesion.6
Our data therefore suggest that recurrence rates are low following EMR (either piecemeal or en bloc) for either G- or F-type LSTs, where recurrence in Brooker’s series of sessile polypectomy without argon plasma coagulation was in excess of 50% at 12 months post polypectomy.27
In conclusion, EMR of both G- and F-type LSTs is a safe and effective management for stage T1 lesions of the colorectum, even in large lesions. We recommend that colonoscopic follow up is performed at six and 12 months post index resection to assess recurrent disease status where a further EMR can be performed if required. Chromoscopy and HMC may be helpful tools given this scenario. Accordingly, EMR may provide an alternative to surgery in selected patients.