Resection Of Early Colorectal Cancer Research Articles

A comparative analysis of different reduced-port laparoscopic surgical procedures after non-curative endoscopic resection for early colorectal cancer

A comparative analysis of different reduced-port laparoscopic surgical procedures after non-curative endoscopic resection for early colorectal cancer

Endoscopic treatment of colorectal polyps and early colorectal cancer

Background: Colonoscopy offers higher diagnostic sensitivity than other colorectal cancer screening methods and provides the advantage of both diagnostic tissue sampling and polyp removal. Since the majority of colorectal cancers evolve from adenomatous polyps, polyp resection through colonoscopy is widely considered an effective method of preventing colorectal cancer and reducing mortality rates.Current Concepts: Determining colorectal polyp size and shape requires comprehensive endoscopy with enhanced imaging techniques to choose treatment directions and the appropriate colorectal polypectomy method. The selection of the polypectomy method is contingent upon the polyp’s attributes and possible malignancy according to US Multi-Society Task Force on Colorectal Cancer and European gastrointestinal endoscopy guidelines. This article examines eight polypectomy procedures: cold forceps polypectomy, hot biopsy polypectomy, cold snare polypectomy, hot snare polypectomy, endoscopic mucosal resection (EMR), and modified EMR techniques. Each method has unique benefits and is suitable for particular polyp types and sizes. Piecemeal EMR and endoscopic submucosal dissection offer alternatives for larger or challenging lesions that require careful planning and follow-up. After endoscopic resection of early colorectal cancer, further surgery may be necessary depending on the risk of lymph node metastasis as determined by specific histologic findings following Korean and Japanese guidelines.Discussion and Conclusion: The choice of endoscopic resection technique, which depends on factors such as polyp shape, size, and location as well as endoscopist skill, is crucial for ensuring complete polyp removal.

Risk factors for residual cancer or lymph node metastasis after endoscopic noncurable resection of early colorectal cancer

Objective: Risk factors related to residual cancer or lymph node metastasis after endoscopic non-curative resection of early colorectal cancer were analyzed to predict the risk of residual cancer or lymph node metastasis, optimize the indications of radical surgical surgery, and avoid excessive additional surgical operations. Methods: Clinical data of 81 patients who received endoscopic treatment for early colorectal cancer in the Department of Endoscopy, Cancer Hospital, Chinese Academy of Medical Sciences from 2009 to 2019 and received additional radical surgical surgery after endoscopic resection with pathological indication of non-curative resection were collected to analyze the relationship between various factors and the risk of residual cancer or lymph node metastasis after endoscopic resection. Results: Of the 81 patients, 17 (21.0%) were positive for residual cancer or lymph node metastasis, while 64 (79.0%) were negative. Among 17 patients with residual cancer or positive lymph node metastasis, 3 patients had only residual cancer (2 patients with positive vertical cutting edge). 11 patients had only lymph node metastasis, and 3 patients had both residual cancer and lymph node metastasis. Lesion location, poorly differentiated cancer, depth of submucosal invasion ≥2 000 μm, venous invasion were associated with residual cancer or lymph node metastasis after endoscopic (P<0.05). Logistic multivariate regression analysis showed that poorly differentiated cancer (OR=5.513, 95% CI: 1.423, 21.352, P=0.013) was an independent risk factor for residual cancer or lymph node metastasis after endoscopic non-curative resection of early colorectal cancer. Conclusions: For early colorectal cancer after endoscopic non-curable resection, residual cancer or lymph node metastasis is associated with poorly differentiated cancer, depth of submucosal invasion ≥2 000 μm, venous invasion and the lesions are located in the descending colon, transverse colon, ascending colon and cecum with the postoperative mucosal pathology result. For early colorectal cancer, poorly differentiated cancer is an independent risk factor for residual cancer or lymph node metastasis after endoscopic non-curative resection, which is suggested that radical surgery should be added after endoscopic treatment.

Comparative analysis of endoscopic submucosal dissection and surgical resection for early colorectal cancer

The OBJECTIVE was a comparative assessment of the efficacy and safety of surgical resection and endoscopic submucosal dissection in the treatment of early colorectal cancer.MATERIALS AND METHODS. We retrospectively evaluated 165 patients after endoscopic submucosal dissection (main group) and 70 patients after surgical resection (control group) with Tis-T1N0M0 stage of colorectal cancer. Median age was 65 and 67. According to the histological structure, the groups consisted mainly of differentiated types of adenocarcinoma.RESULTS. In the endoscopic group, all tumors were removed in a single block. Radical removal was recognized in 80.7% of cases. No progression was detected during the follow-up period. In the group of surgical resections,  progression was detected in 1 patient Postoperative complications in the endoscopic group were 9%, in the surgical group – 35.7%, class 3a and higher according to clavien–Dindo, 4.2 and 25.7%, respectively. When the tumor was localized in the rectum and rectosigmoid bend, there were significantly fewer complications in the main group than in the comparison group (4.2% vs. 20%). In the surgical group, a coloor ileostomy was formed temporarily in 28.6 % of cases, and in 10 % – for perpetuity. There were no treatment-related deaths in both groups.CONCLUSION. In this study, endoscopic submucosal dissection showed a technical success in 100% of cases, with a risk of major postoperative complications of 4.2% and radicality in 80.7% of cases. Standard surgical techniques, along with high oncological efficiency, show significant rate of major complications (25.7 %) and in 38.6 % of cases led to a temporary or permanent life-quality recession. Thus, endoscopic submucosal dissection, in the absence of a negative prognosis factors, is the method of choice in the radical treatment of colon cancer Tis-T1N0M0 due to its effectiveness and safety.

Early colorectal cancer diagnosed after endoscopic resection: Conservative treatment is safe in most of the cases. Proposal for a risk-based management

IntroductionEndoscopic resection offers advantages over surgical resection for early colorectal cancer (ECC). However, there might be a presumed risk of recurrence. We aimed to determine the risk of recurrence after endoscopic removal of ECC. MethodsA single-centre series of endoscopic resections for ECC. Patients were stratified according to four risk factors: positive resection margins, Haggitt 4, lymphatic/vascular invasion and tumour budding. ResultsWe included 127 patients. Haggitt classification was grade 4 in 54.0%. Positive margins were found in 43 (33.9%), 16 (12.6%) had lymphatic or vascular invasion, and 5 (4.0%) had high grade budding. In 82 (64.5%) endoscopic excision was the definitive treatment, 45 (35.4%) underwent surgery. Six patients (13.3%) had residual tumour on specimen and/or node metastases. Postoperative complications occurred in ten (22.2%). At a median follow-up of 63 months, none of the 82 patients treated with endoscopic resection alone had recurrence. After stratifying patients according to risk factors, those who had residual tumour also had ≥2 risk factors. ConclusionsEndoscopic follow up might be a valid option for patients with ECC. A risk-adjusted management seems prudent.

Minimally invasive treatments for early colorectal cancer: comparison of endoscopic resection and laparoscopic surgery.

Endoscopic treatment and laparoscopic surgery are minimally invasive options for early treatment of colorectal cancer, however, more evidence of the long-term outcomes between the two procedures is needed to guide clinical decisions. Therefore, this study aimed to compare the oncologic outcomes between endoscopic and laparoscopic treatment for early colorectal cancer. The study group included 60 patients who underwent endoscopic treatment and 38 patients who underwent laparoscopic surgery for early colorectal adenocarcinoma between January 2010 and December 2013 at a single study site. Histopathological diagnoses showed that 43 (78.3%) carcinomas in the endoscopic submucosal dissection group were mucosal to sm1, 13 (21.7%) were sm2 or deeper, and 17 high-risk cases (28.3%) in the endoscopic group underwent additional surgery. The median operation time, time to sips of water, and length of hospital stay were significantly shorter in the endoscopic group than in the laparoscopic group. The overall survival rates of patients in the endoscopic group and laparoscopic groups were 91.5% and 87.4%, respectively (P=0.391), and the disease-free survival rates were 90.4% and 87.4% (P=0.614), respectively. Systemic recurrences occurred in two patients (1.6%) in the endoscopic group and one patient (2.0%) in the laparoscopic group. Local recurrence combined with systemic recurrence in one patient (0.8%) in the endoscopic group. Endoscopic resection for early colorectal cancer can be performed safely with better short-term outcomes and comparable long-term oncological outcomes compared to laparoscopic surgery.

Influence of early colorectal cancer component on the positive margins after endoscopic resection: a retrospective study

BackgroundEndoscopic treatment methods for early colorectal cancer (ECRC) mainly depend on the size and morphology. It is unclear whether different endoscopic resection methods could achieve curative resection for ECRC confined in the mucosa. The study was designed to compare the rate of positive vertical margin (VM) of ECRC with advanced adenomas (AAs) including adenoma > 1 cm, villous adenoma, high-grade intraepithelial neoplasia/dysplasia stratified by different endoscopic resection methods.MethodsRate of positive VM for 489 ECRCs including Intramucosal (pTis) and superficial submucosal invasion (pT1) carcinomas were compared with those of 753 AAs stratified by different endoscopic resection methods using Chi-squared test. Multivariate logistic model was performed to investigate the risk factors of positive VM for different endoscopic resection methods.ResultsThe pTis ECRC exhibited a similar rate of positive VM as that of AAs for en bloc hot snare polypectomy (HSP, 0% Vs. 0.85%, P = 0.617), endoscopic mucosal resection (EMR, 0.81% vs. 0.25%, P = 0.375) and endoscopic submucosal dissection (ESD, 1.82% Vs. 1.02%, P = 0.659). The pTis carcinoma was not found to be a risk factor for positive VM by en bloc EMR (P = 0.349) or ESD (P = 0.368). The en bloc resection achieved for pT1a carcinomas exhibited similar to positive VM achieved through ESD (2.06% Vs. 1.02%, P = 1.000) for AAs. Nonetheless, EMR resulted in higher risk of positive VM (5.41% Vs. 0.25%, P < 0.001) for pT1a carcinomas as compared to AAs. The pT1a invasion was identified as a risk factor for positive VM in polyps with en bloc EMR (odds ratio = 23.90, P = 0.005) but not ESD (OR = 2.96, P = 0.396).ConclusionCollectively, the pTis carcinoma was not found to be a risk factor for positive VM resected by en bloc HSP, EMR or ESD. Additionally, ESD may be preferred over EMR for pT1a carcinomas with lower rate of positive VM.

Early colorectal cancer diagnosed after endoscopic resection: Conservative treatment is safe in most of the cases. Proposal for a risk-based management

IntroductionEndoscopic resection offers advantages over surgical resection for early colorectal cancer (ECC). However, there might be a presumed risk of recurrence. We aimed to determine the risk of recurrence after endoscopic removal of ECC. MethodsA single-centre series of endoscopic resections for ECC. Patients were stratified according to four risk factors: positive resection margins, Haggitt 4, lymphatic/vascular invasion and tumour budding. ResultsWe included 127 patients. Haggitt classification was grade 4 in 54.0%. Positive margins were found in 43 (33.9%), 16 (12.6%) had lymphatic or vascular invasion, and 5 (4.0%) had high grade budding. In 82 (64.5%) endoscopic excision was the definitive treatment, 45 (35.4%) underwent surgery. Six patients (13.3%) had residual tumour on specimen and/or node metastases. Postoperative complications occurred in ten (22.2%). At a median follow-up of 63 months, none of the 82 patients treated with endoscopic resection alone had recurrence. After stratifying patients according to risk factors, those who had residual tumour also had ≥2 risk factors. ConclusionsEndoscopic follow up might be a valid option for patients with ECC. A risk-adjusted management seems prudent.

Retrospective analysis of LNM risk factors and the effect of chemotherapy in early colorectal cancer: A Chinese multicenter study

BackgroundEstimating the risk of lymph node metastasis (LNM) is crucial for determining subsequent treatments following curative resection of early colorectal cancer (ECC). This multicenter study analyzed the risk factors of LNM and the effectiveness of postoperative chemotherapy in patients with ECC.MethodsWe retrospectively analyzed the data of 473 patients with ECC who underwent general surgery in five hospitals between January 2007 and October 2018. The correlations between LNM and sex, age, tumor size, tumor location, endoscopic morphology, pathology, depth of invasion and tumor budding (TB) were directly estimated based on postoperative pathological analysis. We also observed the overall survival (OS) and recurrence in ECC patients with and without LNM after matching according to baseline measures.ResultsIn total, 473 ECC patients were observed, 288 patients were enrolled, and 17 patients had LNM (5.90%). The univariate analysis revealed that tumor size, pathology, and lymphovascular invasion were associated with LNM in ECC (P = 0.026, 0.000, and 0.000, respectively), and the multivariate logistic regression confirmed that tumor size, pathology, and lymphovascular invasion were risk factors for LNM (P = 0.021, 0.023, and 0.001, respectively). There were no significant differences in OS and recurrence between the ECC patients with and without LNM after matching based on baseline measures (P = 0.158 and 0.346, respectively), and no significant difference was observed between chemotherapy and no chemotherapy in ECC patients without LNM after surgery (P = 0.729 and 0.052).ConclusionTumor size, pathology, and lymphovascular invasion are risk factors for predicting LNM in ECC patients. Adjuvant chemotherapy could improve OS and recurrence in patients with LNM but not always in ECC patients without LNM.

[Retrospective investigation of patients receiving additional surgery after endoscopic non-curative resection for early colorectal cancer].

Objective: To investigate the clinical application of additional surgery after non-curative endoscopic resection for early colorectal cancer. Methods: A retrospectively descriptive cohort study was conducted. Inclusion criteria: (1) pathologically confirmed primary colorectal adenocarcinoma;(2) receiving additional surgery after endoscopic resection; (3) semi-elective operation. Exclusion criteria: familial adenomatous polyposis, appendiceal neoplasms, anal canal neoplasms, neuroendocrine tumors, and surgery because of perforation or bleeding after endoscopic resection. Indications of additional surgery: (1) pathologically positive lateral or basal resection margin; (2) submucosal invasion depth ≥ 1000 μm; (3) lymphovascular invasion; (4) poorly differentiated, undifferentiated or mucinous adenocarcinoma; (5) more than grade G2 in tumor budding; (6) incomplete resection or piecemeal specimen with margin impossible to evaluate; (7) patient's consent due to undetermined pathology. According to the above criteria, clinical data of 92 patients at the Colorectal Surgery Department, the First Affiliated Hospital of Nanjing Medical University between January 2013 and December 2018 were collected. Demographic data, pathological examinations, operative methods and outcomes were analyzed. Results: There were 61 (66.3%) male and 31 female (33.7%) patients with an average age of (58.2±10.7) years. The average BMI was (23.8±3.5) kg/m(2). The lesions located in the right-sided colon, left-sided colon and rectum in 19, 37 and 36 patients respectively. Sixteen patients received endoscopic snare resection, 45 received endoscopic mucosal resection and 31 received endoscopic submucosal dissection. Reasons for additional surgery included endoscopic specimen with pathologically positive margin (n=22, 23.9%), submucosal invasion depth ≥ 1000 μm (n=9, 9.8%), lymphovascular invasion (n=4, 4.3%), poorly differentiated, undifferentiated or mucinous adenocarcinoma (n=5, 5.4%), piecemeal resection (n=13, 14.1%), undetermined pathology (n=52, 56.5%). The median duration from endoscopic resection to additional surgery was 16 days. Thirty-four patients (37.0%) received preoperative endoscopic localization with carbon nanoparticles suspension injection and 5 (5.4%) were marked with titanium clip. Seventy-four patients (80.4%) received laparoscopic surgery, 17 (18.5%) received open surgery, while 1 patient (1.1%) was converted to open surgery due to missing titanium clip. Three patients (3.3%) were treated with transanal excision, 2 (2.2%) with bowel resection, and 87 (94.6%) with radical excision. After additional surgery, histopathological examination of surgical specimens revealed the presence of residual tumor in 5 patients (5.4%), lymph node metastasis in 8 (8.7%), lymphovascular invasion in 1 (1.1%) and tumor deposit in 1 (1.1%). Twelve patients (13.0%) developed postoperative complications, including 4 mid-low rectal cancer patients (4.3%) with anastomostic leakage or bleeding. After surgery, according to the TNM staging system, 83 patients (90.2%) were classified as TNM stage 0-I, 9 (9.8%) as TNM stage II-IV. One patient of stage IV with liver metastasis underwent concomitant hepatectomy. One patient of stage II received regular follow-up after operation. Seven cases of stage III and 1 of stage IV received postoperative chemotherapy. Eighty-five patients (92.4%) were followed up with a median time of 12.8 (IQR: 8.1, 24.3) months. No recurrence or metastasis was observed. Conclusions: Surgery is an effective salvage measure for non-curative endoscopic resection of early colorectal cancer. Since surgery may have complications, indications of the additional surgery should be considered carefully. Preoperative endoscopic localization should be performed in order to ensure the safety and efficacy of surgery.

A real world analysis of recurrence risk factors for early colorectal cancer T1 treated with standard endoscopic resection.

Currently, endoscopic resection of early colorectal cancer defined as carcinoma with limited invasion of the mucosa (Tis) and submucosa (T1) is possible. However, lymph node spreading increases to 16.2% of cases when tumor invades the submucosa. We analyzed the previously identified factors for lymph node dissemination and recurrence, in our population. We analyzed retrospectively all patients with T1 tumors, treated at our center with endoscopic resection and some with additional surgery between January 2006 and January 2018. Statistical analysis was performed using IBM SPSS Statistics 25.0. One hundred fifty-nine patients were treated with endoscopic resection, 56.6% with additional surgery. The mean age was 68.74years and 69. 9% were male. All patients who underwent additional surgery presented negative margins and 8.8% presented positive lymph nodes. In a mean follow-up of 23.36months, 13 patients had relapsed. The risk of relapse did not differ between patients treated with additional surgery from those who only underwent endoscopic resection (p= 0.506). On the other hand, lymph node dissemination (p= 0.007) and a positive endoscopic margin (p= 0.01) were independent risk factors for relapse. There was a positive association between lymph node dissemination and lymphatic (p= 0.07), vascular (p= 0.007), and perineural (p= 0.001) invasion and also with degree of histological differentiation (p= 0.001). In our study, lymphatic, vascular, and perineural invasion and also the degree of histological differentiation were associated with lymph node dissemination. However, the only independent risk factors for long-term recurrence were a positive margin and lymph node dissemination.

[Essential and interpretation of Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines 2019 for the treatment of colorectal cancer].

The Japanese Society for Cancer of the Colon and Rectum (JSCCR) published the guidelines 2019 for the treatment of colorectal cancer in March 2019. The new edition expanded the indications of endoscopic treatment, enriched the follow-up recommendations after endoscopic resection of early colorectal cancer, supplemented the indications of ISR and added the recommendations of lymph node recurrence and peritoneal recurrence. In the new edition, the adjuvant and palliative chemotherapy schemes were revised and patients with first-line chemotherapy were divided into three categories as follows: appropriate for intensive systemic therapy (fit), inappropriate for intensive systemic therapy (vulnerable), and inappropriate for systemic therapy (frail). The new edition of guidelines can also provide references to the doctors of colorectal cancer in our country. This article intends to interpret the essentials of this new edition.

Endoscopic full-thickness resection for early colorectal cancer

Current international guidelines recommend endoscopic resection for T1 colorectal cancer (CRC) with low-risk histology features and oncologic resection for those at high risk of lymphatic metastasis. Exact risk stratification is therefore crucial to avoid under-treatment as well as over-treatment. Endoscopic full-thickness resection (EFTR) has shown to be effective for treatment of non-lifting benign lesions. In this multicenter, retrospective study we aimed to evaluate efficacy, safety, and clinical value of EFTR for early CRC. Records of 1234 patients undergoing EFTR for various indications at 96 centers were screened for eligibility. A total of 156 patients with histologic evidence of adenocarcinoma were identified. This cohort included 64 cases undergoing EFTR after incomplete resection of a malignant polyp (group 1) and 92 non-lifting lesions (group 2). Endpoints of the study were: technical success, R0-resection, adverse events, and successful discrimination of high-risk versus low-risk tumors. Technical success was achieved in 144 out of 156 (92.3%). Mean procedural time was 42 minutes. R0 resection was achieved in 112 of 156 (71.8%). Subgroup analysis showed a R0 resection rate of 87.5% in Group 1 and 60.9% in Group 2 (P < .001). Severe procedure-related adverse events were recorded in 3.9% of patients. Discrimination between high-risk versus low-risk tumor was successful in 155 of 156 cases (99.3%). In Group 1, 84.1% were identified as low-risk lesions, whereas 16.3% in group 2 had low-risk features. In total, 53 patients (34%) underwent oncologic resection due to high-risk features whereas 98 patients (62%) were followed endoscopically. In early colorectal cancer, EFTR is technically feasible and safe. It allows exact histological risk stratification and can avoid surgery for low-risk lesions. Prospective studies are required to further define indications for EFTR in malignant colorectal lesions and to evaluate long-term outcome.

Long-term oncological outcomes of local excision versus radical resection for early colorectal cancer in young patients without preoperative chemoradiotherapy: a population-based propensity matching study.

The incidence and mortality of colorectal carcinoma are rising in young adults. This population‐based propensity matching study aimed to compare long‐term oncological outcomes of local excision with radical resection for early localized colorectal cancer (CRC) in young patients without preoperative chemoradiotherapy. Patients under 45 years old with T1 colon or rectal adenocarcinoma who underwent local excision or radical resection were included from the Surveillance, Epidemiology, and End Results (SEER) database between 1998 and 2014. Survival curves were plotted using the Kaplan–Meier method. Cancer‐specific survival (CSS) was compared using adjusted hazard ratios (HRs) between local excision and radical resection. After propensity score matching procedure, total of 1719 patients were included in the analysis, among which 573 treated with local excision and 1146 treated with radical resection. The median follow‐up was 80 months (interquartile range(IQR): 37–132), with 1074 patients followed for ≥5 years and 508 patients followed for ≥10 years. Five‐year CSS of local excision versus radical resection was 93.4% versus 96.7% for colon cancer and 96.6% versus 98.4% for rectal cancer. Ten‐year CSS of local excision versus radical resection was 91.4% versus 94.0% for colon cancer and 92.8% versus 96.7% for rectal cancer. On multivariable analysis, compared with radical resection, local excision was not associated with inferior CSS for colon (HR 1.74, 95% CI: 0.92–3.29, P = 0.090) and rectal cancer (HR 2.16, 95% CI: 0.99–4.71, P = 0.052). There is no evidence of differential long‐term oncological outcomes between local excision and radical resection. These findings supported clinical application of local excision for early colon and rectal cancer in young adults.

Video Comment on Je-Wook Shin et al.

See also: Risk of recurrence after endoscopic resection of early colorectal cancer with positive marginsEndoscopy eFirstDOI: 10.1055/s-0043-120441

A real world analysis of recurrence risk factors for early colorectal cancer T1 treated with standard endoscopic resection.

575 Background: Currently, endoscopic resection of early colorectal cancer (ECC) defined as carcinoma with invasion limited to the mucosa (Tis), and submucosa (T1) is possible due to advances in instrumentation. However, when tumor invades submucosal layer, lymph node dissemination is present in 16.2% of cases, requiring additional surgery and limfadenectomy. Risk factors for lymph node dissemination and independent for relapse have been previously described in literature. Methods: We performed a retrospective analysis of all patients with colorectal T1 tumors, treated at our center with endoscopic resection and some with additional surgery between 2006 and 2017. Stadistical analysis was perfomed with IBM SPSS Statistics 24.0. Results: 159 patients (p) were treated with endoscopic resection, 56.6% (90p) underwent additional surgery. Mean age was 68.74 years and 69.9% (111p) were male. Endoscopic resection: negative margins 87.6%, vascular 3.1%, lymphatic 2.5% and perineural invasion 3.8%, high degree of histological differentiation 1.3%. Surgical resection: negative margins 100%, lymph node spread 8.8%. In a mean follow-up of 23.36 months since endoscopic treatment, 13 patients had relapsed. Risk of relapse did not differ between patients who received additional surgery and those who only underwent endoscopic resection (p = 0.791). On the other hand, lymph node dissemination (p = 0.007) and a positive margin (p = 0.01) were independent risk factors for risk of relapse. Vascular, lymphatic and perineural invasion, nor degree of histological differentation were stadistically significant. However, there was a positive association between lymph node dissemination and lymphatic (p = 0.07), vascular (p = 0.007) and perineural (p = 0.001) invasion and also degree of histological differentiation (p = 0.000). Conclusions: In our study, relapse rate was under 10% in eleven years. The only independent risk factors for relapse were a positive margin and lymph node dissemination. Perineural, vascular and lymphatic invasion obtained from polypectomy sample, could infer the probability of positive lymph nodes and indirectly be an indicator for risk of relapse.

Risk of recurrence after endoscopic resection of early colorectal cancer with positive margins.

Additional surgery is recommended if an endoscopically resected T1 colorectal cancer (CRC) specimen shows a positive resection margin. We aimed to investigate the significance of a positive resection margin in endoscopically resected T1 CRC. We enrolled 265 patients with T1 CRC who underwent endoscopic resection between January 2001 and December 2016. The inclusion criteria were: 1) complete resection by endoscopy, and 2) pathology of a positive margin. Among the 265 patients, 213 underwent additional surgery and 52 did not. In the additional surgery group, various clinicopathological factors were evaluated with respect to the presence or absence of residual tumor. The follow-up results were assessed in the group that did not undergo additional surgery. In the 213 patients who underwent additional surgery, residual tumor was detected in 13 patients (6.1 %), and none of the clinicopathological factors was significantly associated with the presence of residual tumor. Among the 52 patients who did not undergo additional surgery, recurrence was detected in 4 (7.7 %), and all 4 underwent salvage surgery. Among these four patients, three had no risk factors for lymph node metastasis and recurrence was at the previous resection site; pathology was high grade dysplasia, rpT3N0M0, and rpT1N0M0, respectively. A positive resection margin in endoscopically resected T1 CRC is related to a relatively low incidence of residual tumor (6.1 %). Although current guidelines recommend additional surgery for such cases, surveillance and timely salvage surgery could be another option in selected cases.

P-289 - Association of poor differentiation or positive vertical margin with residual disease in patients with subsequent colectomy after complete macroscopic endoscopic resection of early colorectal cancer

Introduction: In presence of unfavorable pathologic results after endoscopic resection of colorectal cancer, colectomy is routinely performed. We determined the risk factors for residual diseases in patients with colectomy after complete macroscopic endoscopic resection of early colorectal cancer. Methods: We identified consecutive patients who underwent endoscopic resection of early colorectal cancer and subsequently underwent colectomy, from January 2011 to December 2014. Clinicopathologic risk factors related to the residual disease were analyzed. Results: In total, 148 patients underwent endoscopic resection and subsequent colectomy. Residual disease on colectomy was noted in 16 (10.9%) patients. The rates of poorly differentiated/mucinous histology (p = 0.028), and of positive or unknown vertical resection margin (p = 0.047) were higher in patients with residual disease than in those without. In multivariate analysis, a poorly differentiated/mucinous histology and positive or unknown vertical resection margin were significantly associated with residual disease (odds ratio = 7.508 and 2.048, p = 0.015 and 0.049, respectively). Conclusion: After complete macroscopic endoscopic resection of early colorectal cancer, there is a greater need for additional colectomy in cases with a positive or unknown vertical resection margin or a poorly differentiated/mucinous histology, because of their higher risk of residual cancer and lymph node metastasis.

Clinical outcomes of positive resection margins after endoscopic resection of early colorectal cancer.

688 Background: The management of patients with a positive resection margin after endoscopic resection of early colorectal cancer (ECC) depends on various clinical factors, including the pathology. There is little information on the clinical outcomes according to the subsequent management of a positive resection margin in patients with ECC treated by endoscopic resection. We assessed the management according to the pathology of the positive margin and evaluated the clinical outcomes. Methods: Consecutive patients with ECC who underwent endoscopic resection from January 2004 to December 2014 were reviewed. This study retrospectively analyzed 363 lesions from 338 patients (mean age, 60.1 years; 68% [230/338] male). Results: The resection margin was positive in 29.2% of patients, including cancer cells in 9.9%, adenoma in 16.5%, and high-grade dysplasia (HGD) in 2.8%. Subsequent surgery was performed on 11.8% of patients, 72.2% (26/43) of whom were cancer cell–positive, while 23.3% (10/43) were resection margin–negative but had deep submucosal (SM) or lymphatic invasion. Remnant cancer cells were identified in 25.6% (11/43) of the operated group and 81.8% (9/11) of the cancer cell–positive group. On early follow-up surveillance colonoscopy (mean interval, 3.57 months) in 88.2% of patients (320/363), including 95.7% (67/70) of the adenoma and HGD-positive group, only one (0.3%, 1/320) case of remnant adenoma was found. In the multivariate analysis, deep SM invasion ( p=0.026), number of pieces of piecemeal resection (p=0.03) and cancer cell positivity ( p=0.001) predicted subsequent surgery. In the multivariate analysis, an endoscopic appearance of incomplete resection ( p=0.002) and cancer cell positivity (p=0.041) were related to the identification of remnant cancer cells after subsequent surgery. Conclusions: Patients with an adenoma-positive resection margin had favorable clinical outcomes during subsequent surveillance. The choice of subsequent surgery was related to deep SM invasion and cancer cell–positive resection margins, and subsequent surgery group showed a high rate of remnant cancer cells.

Association of Poor Differentiation or Positive Vertical Margin with Residual Disease in Patients with Subsequent Colectomy after Complete Macroscopic Endoscopic Resection of Early Colorectal Cancer.

In the presence of unfavorable pathologic results after endoscopic resection of colorectal cancer, colectomy is routinely performed. We determined the risk factors for residual diseases in patients with colectomy after complete macroscopic endoscopic resection of early colorectal cancer. We identified consecutive patients who underwent endoscopic resection of early colorectal cancer and subsequently underwent colectomy, from January 2011 to December 2014. Clinicopathologic risk factors related to the residual disease were analyzed. In total, 148 patients underwent endoscopic resection and subsequent colectomy. Residual disease on colectomy was noted in 16 (10.9%) patients. The rates of poorly differentiated/mucinous histology (p = 0.028) and of positive or unknown vertical resection margin (p = 0.047) were higher in patients with residual disease than in those without. In multivariate analysis, a poorly differentiated/mucinous histology and positive or unknown vertical resection margin were significantly associated with residual disease (odds ratio = 7.508 and 2.048, p = 0.015 and 0.049, resp.). After complete macroscopic endoscopic resection of early colorectal cancer, there is a greater need for additional colectomy in cases with a positive or unknown vertical resection margin or a poorly differentiated/mucinous histology, because of their higher risk of residual cancer and lymph node metastasis.