Metastasis of primary gallbladder carcinoma in lymph node and liver

AIM: To evaluate the patterns with metastasis of gallbladder carcinoma in lymph nodes and liver. METHODS: A total of 45 patients who had radical surgery were selected. The patterns with metastasis of primary gallbladder carcinoma in lymph nodes and liver were examined histopathologically and classified as TNM staging of the American Joint Committee on Cancer. RESULTS: Of the 45 patients, 29 (64.4%) had a lymph node positive disease and 20 (44.4%) had a direct invasion of the liver. The frequency of involvement of lymph nodes was strongly influenced by the depth of the primary tumor (P= 0.0001). The postoperative survival rate of patients with negative lymph node metastasis was significantly higher than that of patients with positive lymph node metastasis (P= 0.004), but the postoperative survival rate of patients with Nl lymph node metastasis was not significantly different from that of patients with N2 lymph node metastasis (P= 0.3874). The postoperative survival rate of patients without hepatic invasion was significantly better than that of patients with hepatic invasion (P= 0.0177). CONCLUSION: Complete resection of the regional lymph nodes is important in advanced primary gallbladder carcinoma (PGC). The initial sites of liver spread are located mostly in segments IV and V. It is necessary to achieve negative surgical margins 2 cm from the tumor. In patients with hepatic hilum invasion, extended right hepatectomy with or without bile duct resection or portal vein resection is necessary for curative resection.     

Vascular invasion, perineural invasion, and tumour budding: predictors of outcome in colorectal cancer

Tumour stage reflected by the AJCC/UICC TNM system is currently regarded as the most powerful prognostic parameter in patients with colorectal cancer. However, additional histopathological markers are required to improve clinical decision-making with respect to follow-up scheduling and administration of adjuvant therapy. In this review we summarize the available literature regarding the prognostic impact of venous and lymphatic invasion, perineural invasion and tumour budding in colorectal cancer. Special emphasis was placed on patients with AJCC/UICC stage II disease, the risk of lymph node metastasis in early cancer and the prediction of local recurrence in rectal cancer. For each of the markers, the different methods of evaluation, implications resulting from different definitions used in previous studies as well as future perspectives are discussed in detail.     

Digestive cancer surgery in the era of sentinel node and epithelial-mesenchymal transition

Lymph node involvement is one of the most important prognostic indicators of carcinoma of the digestive tract.Although the therapeutic impact of lymphadenectomy has not been proven and the number of retrieved nodes cannot be considered a measure of successful cancer surgery,an adequate lymph node count should be guaranteed to accurately assess the N-stage through the number of involved nodes,lymph node ratio,number of negative nodes,ratio of negative to positive nodes,and log odds,i.e.,the log of the ratio between the number of positive lymph nodes and the number of negative lymph nodes in digestive carcinomas.As lymphadenectomy is not without complications,sentinel node mapping has been used as the rational procedure to select patients with early digestive carcinoma in whom nodal dissection may be omitted or a more limited nodal dissection may be preferred.However,due to anatomical and technical issues,sentinel node mapping and nodal basin dissection are not yet the standard of care in early digestive cancer.Moreover,in light of the biological,prognostic and therapeutic impact of tumor budding and tumor deposits,two epithelial-mesenchymal transition-related phenomena that are involved in tumor progression,the role of staging and surgical procedures in digestive carcinomas could be redefined.     

Comparison of morphological features in lymph node metastasis between pancreatic neuroendocrine neoplasms and pancreatic ductal adenocarcinomas

BackgroundVarious studies have reported inconsistent results regarding the use of lymph node size for the prediction of metastasis in pancreatic cancer. Further, there is even less information in pNENs. Thus, the clinical accuracy and utility of using lymph node size to predict lymph node metastasis in pNENs has not been fully elucidatedObjectivesThis study aimed to examine differences in lymph node morphology between pancreatic neuroendocrine neoplasms (pNENs) and pancreatic ductal adenocarcinomas (PDACs) to create more accurate diagnostic criteria for lymph node metastasis.MethodsWe assessed 2139 lymph nodes, 773 from pNEN specimens and 1366 from PDAC specimens, surgically resected at our institute between 1994 and 2016. We evaluated the number, shape, size, and presence of metastasis.ResultsSixty-eight lymph nodes from 16 pNEN patients and 109 lymph nodes from 33 PDAC patients were metastatic. There were more lymph nodes sampled per case in the PDAC group than in the pNEN group (31.8 vs. 18.0). Metastatic lymph nodes in pNEN patients were larger and rounder than those in PDAC patients (minor axis: 5.15 mm vs. 3.11 mm; minor axis/major axis ratio: 0.701 vs. 0.626). The correlation between lymph node size and metastasis was stronger in pNENs (r = 0.974) than in PDACs (r = 0.439).ConclusionsLymph node status and morphology are affected by differences in tumor histology. The lymph node minor axis is a reliable parameter for the prediction of lymph node metastasis and has more utility as a predictive marker in pNENs than in PDACs.     

Computed tomography and magnetic resonance imaging evaluation of lymph node metastasis in early colorectal cancer

AIM: To assess the role of computed tomography(CT) and magnetic resonance imaging(MRI) and establish imaging criteria of lymph node metastasis in early colorectal cancer.METHODS: One hundred and sixty patients with early colorectal cancer were evaluated for tumor location, clinical history of polypectomy, depth of tumor invasion, and lymph node metastasis. Two radiologists assessed preoperative CT and/or MRI for the primary tumor site detectability, the presence or absence of regional lymph node, and the size of the largest lymph node. Demographic, imaging, and pathologic findings were compared between the two groups of patients based on pathologic lymph node metastasis and optimal size criterion was obtained.RESULTS: The locations of tumor were ascending, transverse, descending, sigmoid colon, and rectum. One hundred and sixty early colorectal cancers were classified into 3 groups based on the pathological depth of tumor invasion; mucosa, submucosa, and depth unavailable. A total of 20(12.5%) cancers with submucosal invasion showed lymph node metastasis. Lymph nodes were detected on CT or MRI in 53 patients. The detection rate and size of lymph nodes were significantly higher(P = 0.000, P = 0.044, respectively) in patients with pathologic nodal metastasis than in patients without nodal metastasis. Receiver operating curve analysis showed that a cut-off value of 4.1 mm is optimal with a sensitivity of 78.6% and specificity of 75%.CONCLUSION: The short diameter size criterion of≥ 4.1 mm for metastatic lymph nodes was optimal for nodal staging in early colorectal cancer.     

Risk factors of lateral pelvic lymph node metastasis in advanced rectal cancer

Background  To clarify the risk factors of lateral pelvic lymph node (LPLN) metastasis of rectal cancer, we examined associations between LPLN status and clinicopathological factors including LPLN status diagnosed by computed tomography (CT). Methods  We reviewed a total of 210 patients with advanced rectal cancer, of which the lower margin was located at or below the peritoneal reflection, who underwent preoperative CT with 5-mm-thick sections and lateral pelvic lymph node dissection at the National Cancer Center Hospital between February 1998 and March 2006. Results  Forty-seven patients (22.4%) had LPLN metastasis. Multivariate analysis showed that LPLN status diagnosed by CT, pathological regional lymph node status, tumor location, and tumor differentiation were significant risk factors for LPLN metastasis. Among 45 patients with well-differentiated adenocarcinoma who were LPLN-negative and in whom CT had found no regional lymph node metastasis, none had LPLN metastasis. On the other hand, among 13 patients with moderate or less differentiated lower rectal adenocarcinoma who were LPLN-positive and in whom CT had revealed regional lymph node metastasis, 12 (92.3%) had LPLN metastasis. Conclusions  LPLN status diagnosed by CT, pathological regional LN status, tumor location, and tumor differentiation are significant risk factors for LPLN metastasis. Using these factors, patients can be classified as having a low or high risk of LPLN metastasis.     

Clinical significance of lymph node metastasis in gastric cancer

Gastric cancer,one of the most common malignancies in the world,frequently reveals lymph node,peritoneum,and liver metastases.Most of gastric cancer patients present with lymph node metastasis when they were initially diagnosed or underwent surgical resection,which results in poor prognosis.Both the depth of tumor invasion and lymph node involvement are considered as the most important prognostic predictors of gastric cancer.Although extended lymphadenectomy was not considered a survival benefit procedure and was reported to be associated with high mortality and morbidity in two randomized controlled European trials,it showed significant superiority in terms of lower locoregional recurrence and disease related deaths compared to limited lymphadenectomy in a 15-year followup study.Almost all clinical investigators have reached a consensus that the predictive efficiency of the number of metastatic lymph nodes is far better than the extent of lymph node metastasis for the prognosis of gastric cancer worldwide,but other nodal metastatic classifications of gastric cancer have been proposed as alternatives to the number of metastatic lymph nodes for improving the predictive efficiency for patient prognosis.It is still controversial over whether the ratio between metastatic and examined lymph nodes is superior to the number of metastatic lymph nodes in prognostic evaluation of gastric cancer.Besides,the negative lymph node count has been increasingly recognized to be an important factor significantly associated with prognosis of gastric cancer.     

Tumor Invasion of Lymph Node Capsules in Patients with Dukes C Colorectal Adenocarcinoma

Purpose The objective of this study was to investigate the correlation between the microscopic findings of positive lymph nodes, especially focusing on capsular invasion, and the outcome after curative surgical resection of colorectal cancer. Methods We analyzed 480 positive lymph nodes from 155 consecutive patients with Stage III colorectal cancer to determine the frequency and significance of lymph node capsular invasion. Recurrence-free and cancer-specific survival rates were assessed in the patients with and without lymph node capsular invasion. Results Between April 1995 and December 2000, 406 consecutive patients with primary colorectal cancer underwent curative resection. Regional lymph node metastases were present in 155 cases (38.2 percent). During the median follow-up period of 4.8 years, 41 patients (26.5 percent) developed recurrent disease and 28 patients died of cancer. Lymph node capsular invasion was detected in one or more lymph nodes from 75 cases (48.3 percent). The five-year recurrence-free rate was 56.1 percent in this group, whereas in the 80 patients without lymph node capsular invasion the rate was 88 percent (P<0.01). Features that were associated with recurrent disease were greater number of positive lymph nodes, venous invasion in primary tumor, infiltrative growth pattern of intranodal tumor, and presence of lymph node capsular invasion. Multivariate analysis identified lymph node capsular invasion as the only significant prognostic factor for recurrence. In multivariate analysis with regard to survival, lymph node capsular invasion, venous invasion, and number of positive nodes remained as significant prognostic factors. Conclusions Lymph node capsular invasion, determined by routine hematoxylin-eosin staining, is a potent prognostic factor in Stage III colorectal cancer. Read in part at the meeting of The International Society of University Colon and Rectal Surgeons, Budapest, Hungary, June 9, 2004. Reprints are not available.     

Prognostic and survival analysis of 837 Chinese colorectal cancer patients

AIM:To develop a prognostic model to predict survival of patients with colorectal cancer (CRC). METHODS:Survival data of 837 CRC patients undergoing surgery between 1996 and 2006 were collected and analyzed by univariate analysis and Cox proportional hazard regression model to reveal the prognostic factors for CRC. All data were recorded using a standard data form and analyzed using SPSS version 18.0 (SPSS, Chicago, IL, United States). Survival curves were calculated by the Kaplan-Meier method. The log rank test was used to assess differences in survival. Univariate hazard ratios and significant and independent predictors of disease-specific survival and were identified by Cox proportional hazard analysis. The stepwise procedure was set to a threshold of 0.05. Statistical significance was defined asP < 0.05. RESULTS:The survival rate was 74% at 3 years and 68% at 5 years. The results of univariate analysis suggested age, preoperative obstruction, serum carcinoembryonic antigen level at diagnosis, status of resection, tumor size, histological grade, pathological type, lymphovascular invasion, invasion of adjacent organs, and tumor node metastasis (TNM) staging were positive prognostic factors (P < 0.05). Lymph node ratio (LNR) was also a strong prognostic factor in stage Ⅲ CRC (P < 0.0001). We divided 341 stage Ⅲ patients into three groups according to LNR values (LNR1, LNR ≤ 0.33, n = 211; LNR2, LNR 0.34-0.66, n = 76; and LNR3, LNR ≥ 0.67, n = 54). Univariate analysis showed a significant statistical difference in 3-year survival among these groups:LNR1, 73%; LNR2, 55%; and LNR3, 42% (P < 0.0001). The multivariate analysis results showed that histological grade, depth of bowel wall invasion, and number of metastatic lymph nodes were the most important prognostic factors for CRC if we did not consider the interaction of the TNM staging system (P < 0.05). When the TNM staging was taken into account, histological grade lost its statistical significance, while the specific TNM staging system s     

Lymph node ratio-based staging system for esophageal squamous cell carcinoma

AIM: To analyze a modified staging system utilizing lymph node ratio (LNR) in patients with esophageal squamous cell carcinoma (ESCC).METHODS: Clinical data of 2011 patients with ESCC who underwent surgical resection alone between January 1995 and June 2010 at the Cancer Hospital of Shantou University Medical College were reviewed. The LNR, or node ratio (Nr) was defined as the ratio of metastatic LNs ompared to the total number of resected LNs. Overall survival between groups was compared with the log-rank test. The cutoff point of LNR was established by grouping patients with 10% increment in Nr, and then combining the neighborhood survival curves using the log-rank test. A new TNrM staging system, was constructed by replacing the American Joint Committee on Cancer (AJCC) N categories with the Nr categories in the new TNM staging system. The time-dependent receiver operating characteristic curves were used to evaluate the predictive performance of the seventh edition AJCC staging system and the TNrM staging system.RESULTS: The median number of resected LNs was 12 (range: 4-44), and 25% and 75% interquartile rangeswere8 and 16. Patients were classified into four Nr categories with distinctive survival differences (Nr0: LNR = 0; Nr1: 0% < LNR ≤ 10%; Nr2: 10% < LNR ≤ 20%; and Nr3: LNR > 20%). From N categories to Nr categories, 557 patients changed their LN stage. The median survival time (MST) for the four Nr categories (Nr0-Nr3) was 155.0 mo, 39.0 mo, 28.0 mo, and 19.0 mo, respectively, and the 5-year overall survival was 61.1%, 41.1%, 33.0%, and 22.9%, respectively (P < 0.001). Overall survival was significantly different for the AJCC N categories when patients were subgrouped into 15 or more vs fewer than 15 examined nodes, except for the N3 category (P = 0.292). However, overall survival was similar when the patients in all four Nr categories were subgrouped into 15 or more vs fewer than 15 nodes. Using the time-dependent receiver operating characteristic, we found that the Nr category and TNrM stage had higher accuracy in predicting survival than the AJCC N category and TNM stage.CONCLUSION: A staging system based on LNR may have better prognostic stratification of patients with ESCC than the current TNM system, especially for those undergoing limited lymphadenectomy.     

颈部淋巴结转移与甲状腺乳头状癌的治疗及预后

颈部淋巴结转移在甲状腺乳头状癌中较为普遍.尽管颈部淋巴结转移可独立预测甲状腺乳头状癌的复发,但其对于肿瘤预后的影响仍有争议.预防性中央区淋巴结对甲状腺乳头状癌患者的价值尚不清楚,尤其是术前无颈部淋巴结转移的临床或影像学证据时.对于存在危险因素的甲状腺乳头状癌患者,如男性、年龄大于45岁、肿瘤直径＞4 cm、多灶性和甲状腺外侵犯以及BRAF基因突变阳性等,术前应认真评估颈部淋巴结,必要时可行预防性中央区淋巴结清扫.     

Isolated tumor cell in lateral lymph node has no influences on the prognosis of rectal cancer patients

BACKGROUND AND AIMS: The aim of this study was to determine the incidence of isolated tumor cells (ITC) and micrometastasis in lateral lymph nodes of patients with rectal cancer and its possible correlation with prognosis. MATERIALS AND METHODS: One hundred seventy-seven rectal cancer patients who underwent curative resection with lateral lymph node dissection were enrolled. Dissected lymph nodes were examined using hematoxylin-eosin staining (HE) and immunohistochemistry (IHC) with anti-keratin antibody (AE1/AE3). States of lymph node metastasis were divisible into three groups: detectable with HE (HE+), detectable with only IHC (HE-/IHC+), and undetectable even with IHC (IHC-). Almost all the HE-/IHC+ group was classified as ITC consisting of a few tumor cells according to the UICC criteria (ITC+). Survival rates were compared among HE+, ITC+, and IHC-. RESULTS: ITC+ were detected in 24.1% of patients with HE-negative lateral lymph nodes. No significant difference in overall 5-year survival was observed between ITC+ and IHC- patients (76.1 and 82.9%, respectively, p = 0.25). Multivariate analysis showed that perirectal HE+ lymph nodes, but not ITC+ lateral lymph nodes, was an independent prognostic factor. CONCLUSIONS: ITC in lateral lymph nodes does not contribute to the prognosis of rectal cancer in patients who undergo extended lateral lymph node dissection, unlike HE+ lateral lymph node metastasis.     

结直肠癌淋巴结转移相关因素的研究进展

结直肠癌淋巴结转移受多种因素的影响,众多因素之间相互联系、相互作用,临床工作中需对各种因素综合分析才能正确地做出诊断和治疗,本文查阅近十年关于结直肠癌淋巴结转移的相关因素的文献,初步总结了目前被普遍认同的影响结直肠癌淋巴结转移的相关因素,为研究结直肠癌淋巴结转移的独立因素提供思路。目前认为肿瘤的浸润深度、原发部位、分化程度、病理类型以及患者的术前血清CEA水平等与结直肠癌的淋巴结转移具有相关性。而肿瘤的大小和大体形态等因素与结直肠癌淋巴结转移是否具有相关性,目前的认识还不一致。造成以上研究结果出现差异的原因可能有:不同学者对于患者选择的差异、样本数量的多少以及采用的标准不同等。     

Nodal spread and micrometastasis within mesorectum

AIM: To study the distribution of positive lymph nodes within mesorectum and to investigate the possible micrometastasis in negative lymph nodes. METHODS:Large slice technique combined with tissue microarray was used in the pathologic study of 31 specimens. RESULTS:A total of 992 lymph nodes were harvested and cancer metastasis was found in 148 lymph nodes. Some positive lymph nodes were located in the outer layer of mesorectum and more at the same site of mesorectum as the primary tumor. Circumferential margin lymph node metastasis was observed in nine cases. No significant difference in occurrence of micrometastasis was observed in different stage tumors. CONCLUSION: Positive lymph nodes are distributed in mesorectum and micrometastasis can be found in negative lymph nodes.     

大肠癌细胞增殖活性与淋巴结转移规律的研究

采用流式细胞术（ＦＣＭ）测定了３０例大肠癌患者新鲜癌组织标本的ＤＮＡ指数（ＤＩ），Ｓ期细胞比率（ＳＰＦ０及增殖指数（ＰＩ），同时对３０例大肠癌患者的淋巴结转移状况按转移个数和转移距离进行分站。结果显示，大肠癌异倍体淋巴结转移率较二倍体淋巴结转移率明显升高。大肠癌淋巴结转移阳性较阴性组ＳＰＦ，ＰＩ明显升高，淋巴结多数转移组较少数转移组，少数转移组较无转移组ＳＰＦ、ＰＩ明显升高，Ｎ２站转移组较Ｎ１ＵＨ     

Reappraisal of the new UICC staging system for gastric cancer: problem in lymph node stage

BACKGROUND/AIMS: The International Union Against Cancer (UICC) TNM staging system defined a new system for classifying gastric cancer, based on the number of metastatic nodes (1997). However, the advantage of the new system is still a matter of debate. The aim of the present study is to compare the new system with the old one (1987), which is based on the location of positive lymph nodes. METHODOLOGY: We analyzed the survival of 608 patients with curative resection of their gastric cancer. The average number of resected and involved lymph nodes for each resected patient was 31.4 and 7.7. Comparison of these two systems was carried out to determine which classification was more effective. The prognostic value of different lymph node staging systems was also analyzed. RESULTS: One hundred and thirty-five patients (22.2%) had different N classification and 109 (17.9%) had different TNM staging. There was a significant stepwise decrease of slope of survival curve for each stage, but the new system did not cleanly separate stage II with IIIa at 3 years and stage IIIb with IV at 5 years. Although different lymph node staging systems were able to predict survival, the ratio rather than the number of involved nodes had a more cleanly separated stepwise decrease of slope of survival curve. CONCLUSIONS: The new UICC staging system is not better than the old system for the staging of gastric cancer. The reason is that the category of node number seems not to be appropriate and will be influenced by the extent of lymph node dissection. To overcome this problem, the frequency of involved nodes can be adopted instead of the number.     

Clinicopathological characteristics and prognosis of rectal well-differentiated neuroendocrine tumors

Background  To clarify the oncological outcome of rectal well-differentiated neuroendocrine tumors (W/D NETs), we examined the clinicopathological characteristics and prognosis of patients with this neoplasm. Materials and methods  A total of 23 patients who underwent surgical treatment with lymph node dissection for rectal W/D NETs between 1973 and 2007 were reviewed. Results  Median tumor size measured preoperatively was 13 mm (range, 4–25 mm), and the median number of dissected lymph nodes was 16 (range, 1–46). The incidence of lymph node metastasis was 61% (14 of 23 cases). The smallest W/D NETs with lymph node metastasis was 10 mm in diameter. All the patients without lymph node metastasis survived without recurrence. Among 11 patients who had only regional lymph node metastasis, only one developed liver metastasis and died 13 months after initial surgery. Among three patients with lateral pelvic lymph node metastasis, two survived more than 5 years, although two had liver metastasis. Conclusions  Because the incidence of lymph node metastasis is very high in patients with rectal W/D NETs greater than 10 mm in diameter, radical surgery is required. In this series, the outcome of rectal W/D NETs patients with lateral pelvic lymph node metastasis was better than expected.     

Risk Stratification of T1 Colorectal Cancer Metastasis to Lymph Nodes: Current Status and Perspective

With the widely spreading population-based screening programs for colorectal cancer and recent improvements in endoscopic diagnosis, the number of endoscopic resections in subjects with T1 colorectal cancer has been increasing. Some reports suggest that endoscopic resection prior to surgical resection of T1 colorectal cancer has no adverse effect on prognosis and contributes to this tendency. The decision on the need for surgical resection as an additional treatment after endoscopic resection of T1 colorectal cancer should be made according to the metastasis risk to lymph nodes based on histopathological findings. Because lymph node metastasis occurs in approximately 10% of patients with T1 colorectal cancer according to current international guidelines, the remaining 90% of patients may be at an increased risk of surgical resection and associated postoperative mortality, with no clinical benefit derived from unnecessary surgical resection. Although a more accurate prediction system for lymph node metastasis is needed to solve this problem, risk stratification for lymph node metastasis remains controversial. In this review, we focus on the current status of risk stratification of T1 colorectal cancer metastasis to lymph nodes and outline future perspectives.     

食管癌环氧化酶-2的高表达与淋巴转移的关系

目的　探讨环氧化酶 -2 (COX -2 )在食管癌中的表达情况及其与淋巴结转移的关系。方法　应用免疫组织化学方法(SP法 ) ,检测 1999～ 2 0 0 1年手术切除的 76例食管癌病人中COX -2的表达。其中有食管旁淋巴结转移者 18例 ,胃左动脉旁淋巴结转移者 11例。结果　COX -2在食管癌中的表达率为 81 6 %,主要为癌组织的表达 ,而在癌旁组织几乎不表达 ;食管癌旁和胃左动脉旁淋巴结转移组COX -2的表达水平均高于未转移组 (P <0 0 0 1)。结论　食管癌中COX -2的高度表达与食管癌的发生、发展及淋巴结转移有关 ,提示COX -2可能是防治食管癌的一个靶位。     

Anatomic study of the lymph nodes of the mesorectum

PURPOSE: Lymph node involvement is the most important prognostic factor when staging patients with colorectal cancer. The probability of detecting metastasis grows with the number of nodes examined. However, the number of nodes found in surgical specimens varies substantially. We have therefore determined the number and distribution of lymph nodes in the mesorectum by cadaveric dissection. METHODS: Twenty formalin-fixed cadaveric pelvises were dissected (13 males). The search for lymph nodes was performed in a systematic way, from the division of the superior rectal artery following the smallest visible branches to the level of the anorectal ring. RESULTS: A total of 168 lymph nodes were found in 20 mesorectal blocks, with a mean (standard deviation) number per specimen of 8.4 (4.45). Lymph node size ranged from 2 to 10 mm. Distribution of lymph nodes in mesorectum was as follows: 120 nodes (71.4 percent) were found around the branches of the superior rectal artery proximal to the peritoneal reflection, and 48 nodes (28.6 percent) were found distal to the peritoneal reflection. Fourteen specimens (70 percent) had lymph nodes at the division of the superior rectal artery. CONCLUSIONS: The mean number of lymph nodes found in the mesorectum distal to the superior rectal artery division was 8.4. Most of these lymph nodes were proximal to the peritoneal reflection. The range found in the number of lymph nodes per case should be considered for use in the formulation of guidelines in anatomicopathologic studies of surgical specimens obtained after mesorectal excision.Poster presentation at the XVI Congreso Latinoamericano de Coloproctología, Santiago, Chile, October 28 to 30, 1999.