Lymphoscintigraphy in patients with primary rectal cancer: the role of total mesorectal excision for primary rectal cancer--a lymphoscintigraphic study

BACKGROUND AND AIMS: Total mesorectal excision based operations is the gold standard of care in patients with middle and lower rectal cancer, but the extent of resection varies widely. In our view, extended lymphadenectomy is unnecessary with precise total mesorectal excision, i.e., anatomically correct and sharp surgery. PATIENTS AND METHODS: Sixteen patients with primary rectal cancer underwent rectal lymphoscintigraphy 1 day prior continence-preserving anterior resection with total mesorectal excision. The specimens were examined for integrity by postoperative angiography of the superior rectal artery in anteroposterior and lateral views. RESULTS: Twelve patients had only mesorectal lymph nodes, and four had additional extramesorectal iliac lymph nodes. The labeled lymph nodes were identified and removed perioperatively using a gamma probe. Activity was measured again in the preparations outside the situs. Histological examination showed tumor-free lymph nodes only. CONCLUSION: Lymph vessels can be divided anatomically into visceral and somatic, and detection of extramesorectal lymph nodes does not call for lateral lymphadenectomy. Primary rectal cancer confined to the organ metastasizes within the mesorectum and does not invade extraregional lymph nodes. The mesorectum is the major visceral route for caudocranial metastatic spread.     

Vascular organization in the mesorectum: angiography of rectal resection specimens

The technical advances in rectal cancer surgery are known as the total mesorectal excision. The resection in an anatomically defined plane under direct vision and with sharp dissection distinguishes it conventional rectal surgery. The result must be a complete mesorectum without deep gouges. We performed specimen angiography to confirm completeness of the removed mesorectum. Thirteen total mesorectal excision specimens were examined by angiography after continence-preserving resection of rectal carcinoma. In 11 of the 13 cases the vascular supply was exclusively via the superior rectal artery. In two cases with hypoplastic left terminating branches of the superior rectal artery there was additional perfusion via a caudally ascending vessel or via smaller vessels connected laterally. In all specimens both arterial supply and venous outflow were located within the mesorectal fascial sheath. There was no radio-opaque substance leaking from the mesorectal surface in the case of a complete mesorectal specimen. Tiny vascular branches running laterally occurred in 7 of the 13 cases. We found no larger vascular connections branching off in the lateral direction. The rectal blood supply comes almost exclusively through the superior rectal vessels. Thus the fascia covering the mesorectum forms, as far as rectal vascularization is concerned, a closed compartment. The mesorectal vessels are enclosed in the fibrous avascular mesorectal fascia. They run close above the fascia. In the case of an incomplete mesorectal excision the specimen angiography shows a stain leaking from the mesorectal fascia. Our method can be used to confirm the completeness of the removed mesorectum.     

Mesorectal Lymph Nodes: Their Location and Distribution Within the Mesorectum

PURPOSE: Total mesorectal excision is an alternative surgical approach for resectable rectal cancer and is associated with favorable results and a low rate of local recurrence. Despite the popularity of this technique, few data exist regarding the location and distribution of lymph nodes within the rectal mesentery. The purpose of this study was to define the distribution, size, and location of lymph nodes within the mesorectum and on the pelvic side wall. METHODS: Seven fresh cadavers at our institution's Fresh Tissue Dissection Laboratory were studied. The rectum, its mesentery, and all fatty tissue from both pelvic side walls were removed and placed in a lymph node clearing solution for 24 hours. After appropriate dissection, the distribution, size, and location of lymph nodes within the rectal mesentery and pelvic side wall tissue were documented. RESULTS: A total of 174 lymph nodes were identified (approximately 25 per patient). The majority (>80 percent) of lymph nodes were smaller than 3 mm in diameter. Fifty-six percent of the nodes within the rectal mesentery were located in the posterior mesentery, and most were located in the upper two-thirds of the posterior rectal mesentery. CONCLUSIONS: The majority of perirectal lymph nodes are small. There are few lymph nodes within the mesentery of the lower third of the rectum and relatively few in the right and left lateral portions of the mesorectum. We confirm that the majority of nodes are located in the proximal two-thirds of the posterior rectal mesentery. It is possible that removal of these nodes is responsible for the superior oncologic results found with total mesorectal excision in contrast to more traditional surgical techniques.     

Studies of the vascular anatomy of the mesorectum support the concept of the total mesorectal excision

The relation between the mesorectal vessels and the mesorectal fascia needs to be clarified, as a total mesorectal excision (TME) probably derives its advantage from the fact that the visceral or mesorectal fascia can be regarded as a “tumor-tight packaging” and does not contain anatomically preformed perforations. The purpose of this investigation was to study both rectal arterial supply and vascular distribution pattern within the mesorectum. The arterial supply to the rectum was studied with the injection technique in 12 porcine and 28 human TME specimens. We stain-marked 12 porcine and 15 human specimens. Thirteen human specimens were angiographed after filling their arterial bed with a radio-opaque substance. The superior rectal artery is the main rectal artery. Terminal branches extend downwards and forward around the rectum to the level of the levator and muscle. The superior rectal artery and vein were found to be enclosed in a fibrous sheath. The main mesorectal vessels do not penetrate the mesorectal fascia. This study supports the hypothesis of bilateral somatic and one central visceral compartment in the pelvis and implies the absolute necessity of tumor removal within an intact mesorectal fascia. Received: 15 August 2000 / Accepted in revised form: 1 October 2000     

Total Mesorectal Excision Results in Low Local Recurrence Rates in Lymph Node-Positive Rectal Cancer

PURPOSE: Most series report lymph node involvement as the main predictor for local recurrence. The principal lymphatic drainage of the rectum is to nodes in the mesorectum and then nodes along the superior rectal and inferior mesenteric arteries. If total mesorectal excision provides adequate block dissection of the lymphatics of the rectum, good local control with low rates of local recurrence should be achieved even in node-positive disease.METHODS: Prospective data on all rectal cancers have been collected since 1978; 170 patients with Dukes C rectal cancer have undergone anterior resection and total mesorectal excision. We did not perform any internal iliac node dissections. Follow-up data were analyzed for local recurrence and distant recurrence.RESULTS: The local recurrence rate was 2 percent for Dukes A cases, 4 percent for Dukes B, and 7.5 percent for Dukes C (P = 0.0127). The systemic recurrence rate was 8 percent for Dukes A, 18 percent for Dukes B, and 37 percent for Dukes C (P = 0.0001).CONCLUSIONS: If surgical priority is given to the difficult task of excision of the whole mesorectum, anterior resection with total mesorectal excision in node-positive rectal cancer, local recurrence rates of < 10 percent can be achieved.Presented at the Association of Colorectal Surgeons of Great Britain and Ireland, Harrogate, United Kingdom, June 25 to 27, 2001.     

Mesorectal Grades Predict Recurrences After Curative Resection for Rectal Cancer

PURPOSE: Local recurrence after curative excision for rectal cancer is frequently regarded as a failure of surgery. The macroscopic quality of the excised mesorectum after total mesorectal excision has been proposed as a means of assessment of the adequacy of surgery. This study was designed to determine the utility of mesorectal grading in prediction of local and overall recurrence after curative surgery. METHODS: All patients undergoing resection for primary adenocarcinoma of the rectum had a mesorectal grading prospectively applied to their resection specimens, according to the classification proposed by Quirke et al. (Grades 1-3; 3 is the best). The outcome of patients undergoing potentially curative surgery from 2001 to 2003 was reviewed. Prognostic significance of mesorectal grades was determined by multivariate regression analyses. RESULTS: A total of 130 patients with a median follow-up of 26 (range, 17-42) months were studied. The local and overall recurrences were 8.4 and 15 percent, respectively. The mesorectum was reported as Grade 3 in 61 patients (47 percent), Grade 2 in 52 patients (40 percent), and Grade 1 in 17 patients (13 percent). Patients with Grade 1 mesorectum had 41 percent local recurrence and 59 percent overall recurrence, respectively. However, patients with Grade 2 and Grade 3 mesorectum had 5.7 and 1.6 percent local recurrences, respectively, and 17 and 1.6 percent overall recurrence, respectively. By Cox's regression analysis, grade of mesorectum independently influenced both local and overall recurrences. CONCLUSIONS: The macroscopic quality of mesorectum after curative excision of rectal cancer is an important predictor of local and overall recurrences. The mesorectal grades may be of value in decisions regarding postoperative adjuvant therapy.     

Lymph Node Metastases of Prostatic Adenocarcinoma in the Mesorectum in Patients With Adenocarcinoma or Villous Tumor of the Rectum With Collision Phenomenon in a Single Lymph Node: Report of Five Cases

PURPOSE Lymph node involvement is the most important prognostic factor when staging patients with rectal cancer. Cancer originating from sites other than rectum rarely may metastasize to the mesorectum. We report five patients with metastatic prostatic carcinoma to mesorectal lymph nodes, with the collision phenomenon in one lymph node. The diagnosis of prostate cancer was clinically unsuspected in two cases.METHODS We examined three cases of primary adenocarcinoma and two villous tumors with high-grade dysplasia (patient age range, 52–74 (mean, 63) years) of the middle or lower third of the rectum. All patients underwent low anterior rectal resection with total mesorectal excision and colorectal or coloanal anastomosis. We used a manual technique for lymph node detection after overnight fixation in 10 percent formalin. All lymph nodes identified (range, 15–32; mean, 21 nodes per patient) were examined histologically.RESULTS Of 106 lymph nodes examined, 20 contained metastases: 9 from rectal adenocarcinoma, 10 from prostatic adenocarcinoma, and 1 with metastatic foci from both tumors. The diagnosis of prostatic carcinoma was readily confirmed by immunostaining for prostatic-specific antigen, and prostatic acid phosphatase.CONCLUSIONS Mesorectal lymph node dissection provides prognostic information in rectal cancer, but careful examination may reveal other unsuspected pathology. Immunohistochemical staining is an essential tool in distinguishing the origin of a lymph node metastasis, especially when the histology does not look typical for rectal carcinoma. Moreover, these observations highlight the connection that can exist between mesorectal lymph node drainage, and extra mesorectal lymph nodes drainage.Reprints are not available.Presented at the meeting of European Association of Coloproctology, Erlangen, Germany, September12 to 14, 2002.     

Tumorangiogenese beim primären Rektumkarzinom Befunde angiographischer Präparatuntersuchungen

Background: One reason for early metastasis formation and/or the occurrence of a tumor relapse is the formation of tumor vessels respectively the penetration of tumor cells in the rectal vessels. The tumor growth of rectal cancer depends on the generation of new vessels. Hematogenous metastazation is encouraged by an increasing vascularization and has a negative influence on the relapse-free period and the long-time survival of the patients. Method: Tumor-associated changes of the superior rectal artery and the superior rectal vein have been evaluated on 31 operation-specimens by subtraction angiography. Results: The arteria rectalis superior physiologically divides into two branches of the same diameter. Both branches follow the mesorectum in an almost symmetrical fashion caudad, accompanied by the corresponding veins. Conclusion: The DSA images showed various changes in the mesorectal arteries due to tumor-associated neovascularisation. The artery trees in all specimens were complete, confirming anatomically a total mesorectal excision.     

Tumor micrometastases in mesorectal lymph nodes and their clinical significance in patients with rectal caner

AIM: To investigate the number, size, and status of lymph nodes within the mesorectum and to explore the prognostic significance of lymph node micrometastases in patients with rectal cancer. METHODS: Thirty-one patients with rectal cancer undergone total mesorectal excision between October 2001 and October 2002 were included. Mesorectal nodes retrieved from the resected specimens were detected with a combination of haematoxylin and eosin (HE) staining and immunohistochemistry (IHC). The relations between lymph node metastases, micrometastases and postoperative recurrence were analyzed. RESULTS: A total of 548 lymph nodes were harvested, with 17.7+/-8.2 nodes per case. The average number of metastatic nodes in HE-positive patients and micrometastatic nodes in IHC-positive patients was 5.2+/-5.1 per case and 2.2+/-1.3 per case, respectively. The mean size of all nodes and metastatic nodes was 4.1+/-1.8 mm and 5.2+/-1.7 mm in diameter, respectively. The mean size of micrometastatic nodes was 3.9+/-1.4 mm in diameter. The size of the majority of mesorectal nodes (66.8%), metastatic nodes (52.6%), and micrometastatic nodes (79.5%) was less than 5 mm in diameter. During a median follow-up period of 24.6+/-4.7 mo, 5 patients (16.7%) had recurrence, of them 2 died and 3 survived. Another case died of tumor unrelated cause and was excluded. All 5 recurrent cases had 3 or more nodes involved, and one of them developed only lymph node micrometastases. The mean number of both metastatic and micrometastatic nodes per case differed significantly between the recurrent and non-recurrent groups (P<0.01 and P = 0.01, respectively). CONCLUSION: The majority of lymph nodes, metastatic, and micrometastatic lymph nodes within the mesorectum are smaller than 5 mm in diameter. The nodal status and the number of lymph nodes involved with tumor metastases and micrometastases are related to the rapid postoperative recurrence.     

Laparoscopic oncologic abdominoperineal resection

PURPOSE: Although the use of laparoscopic techniques in colorectal surgery has recently become a focus of major interest in intestinal surgery, there is no proof that an oncologic abdominoperineal resection can be accomplished using laparoscopic techniques. The hypothesis of this study is that a standardized technique for laparoscopic oncologic abdominoperineal resection according to accepted oncologic surgical principles can be developed in a cadaver model. The end points of this study were intraoperative complications, success in performance of proximal vascular ligation of the inferior mesenteric artery, complete removal of the mesorectum including all lymph nodes adjacent to the named rectal arteries, and wide clearance of pelvic side walls. METHODS: Laparoscopic abdominoperineal resection was performed in 11 fresh cadavers (1 female and 10 males). After surgery, all cadavers underwent autopsy. The number of removed and remaining mesenteric lymph nodes, length of remaining inferior mesenteric artery, and mesorectal and the pelvic side wall soft tissue were evaluated. RESULTS: No major intraoperative complications were recorded. The median number of removed lymph nodes in the mesorectum was 12 (range, 6–22) and no remaining lymph nodes were found at the base of the inferior mesenteric artery. The median length of remaining inferior mesenteric artery was 5 (range, 1–15) mm. Wide lateral clearance of pelvic side walls was noted in all patients. CONCLUSION: A laparoscopic technique of abdominoperineal resection can be performed according to oncologic principles with proximal vascular ligation of inferior mesenteric artery, wide clearance of pelvic side walls, and complete removal of mesorectum using our described technique.Supported in part by the United States Surgical Corporation, Norwalk, Connecticut and the Mexican Army, Mexico.     

Mesorectal microfoci adversely affect the prognosis of patients with rectal cancer

PURPOSE: Mesorectal involvement is a common feature in rectal tumors. Neoplastic foci can be identified at pathologic examination of the mesorectum, but their incidence and prognostic significance remain to be defined. METHODS: A series of 77 patients with extraperitoneal rectal cancer, resected with total mesorectal excision, entered the study. After fixation, the excised specimens were submitted to serial transverse sections and staining. Direct tumor infiltration, lymph node involvement, and neoplastic microfoci in the mesorectum were investigated. Patients with mesorectal foci were compared with those without deposits with regard to clinical and pathologic parameters; different patterns of foci (endovasal, endolymphatic, perineural, isolated) were also considered. Univariate and multivariate analyses were used to evaluate the impact on survival rate. RESULTS: Neoplastic mesorectal involvement was found in 64 patients (83.1 percent). Direct tumor infiltration was detected in 66.2 percent, node involvement in 28.6 percent, microscopic foci in 44.2 percent of cases (endovasal in 11.7 percent, endolymphatic in 15.7 percent, perineural in 26 percent, isolated in 14.3 percent). In 7 cases (10.9 percent) microfoci alone (without any kind of other mesorectal involvement) were detected. Deposits were found in 18.8 percent of TNM Stage I tumors, in 46.9 percent of Stage II and in 59.3 percent of Stage III cancers. Similar incidence was found in patients treated with integrated therapies and surgery alone (43.3 vs. 44.7 percent, P = not significant). Poorer median (44.5 vs. 57 months, P = 0.04) five-year overall survival rate (43.4 vs. 63.3 percent, P = 0.016) and disease-free survival rate (43.3 vs. 57.7 percent, P = 0.048) were observed in patients with microscopic foci compared with those without deposits. Tumor configuration was found to be a independent prognostic factor for both overall and disease-free survival rates; furthermore, endolymphatic, perineural, and isolated foci significantly affected overall survival rate, while TNM staging affected disease-free survival rate. CONCLUSIONS: The incidence of neoplastic foci in the mesorectum is high, even in early staged tumors and despite aggressive preoperative treatment. They seem to affect prognosis. Such features should, therefore, be considered when local excision of the tumor is planned. Presence of mesorectal foci should modify conventional staging of the rectal tumor.     

Discontinuous Rectal Cancer Spread in the Mesorectum and the Optimal Distal Clearance Margin in Situ

PURPOSE: We examined the frequency, mode, and extent of discontinuous spread of rectal cancer in the mesorectum to determine the optimal distal clearance margin in situ. METHODS: Forty consecutive patients with rectal cancer undergoing locally curative resection were studied prospectively. Discontinuous cancer spread in the mesorectum and the extent of distal spread was examined microscopically. A tissue shrinkage ratio comparing the distal clearance margin measured before transection to that measured after fixation in each case, was used to convert microscopically measured extent of distal spread to extent in situ. RESULTS: Discontinuous cancer spread in the mesorectum was observed in 17 cases (43 percent); lymph node metastasis in 15 cases (38 percent) and small deposits other than nodal metastases in 8 cases (20 percent). Distal cancer spread (either intramural or mesorectal) was observed in 6 cases (15 percent). The mean distal clearance margin before transection and after fixation was 3.2 cm and 2 cm, respectively. The mean tissue shrinkage ratio was 60 percent. The maximum extent of microscopic distal spread and adjusted distal spread in situ were 20 and 24 mm, respectively. CONCLUSIONS: Excising the mesorectum with fascia propria circumferentially intact is essential for rectal surgery. The optimal distal clearance margin for the rectal wall as well as the mesorectum in situ can be reduced to 3 cm with a right angle.     

Discontinuous rectal cancer spread in the mesorectum and the optimal distal clearance margin in situ

PURPOSE: We examined the frequency, mode, and extent of discontinuous spread of rectal cancer in the mesorectum to determine the optimal distal clearance margin in situ. METHODS: Forty consecutive patients with rectal cancer undergoing locally curative resection were studied prospectively. Discontinuous cancer spread in the mesorectum and the extent of distal spread was examined microscopically. A tissue shrinkage ratio comparing the distal clearance margin measured before transection to that measured after fixation in each case, was used to convert microscopically measured extent of distal spread to extent in situ. RESULTS: Discontinuous cancer spread in the mesorectum was observed in 17 cases (43 percent); lymph node metastasis in 15 cases (38 percent) and small deposits other than nodal metastases in 8 cases (20 percent). Distal cancer spread (either intramural or mesorectal) was observed in 6 cases (15 percent). The mean distal clearance margin before transection and after fixation was 3.2 cm and 2 cm, respectively. The mean tissue shrinkage ratio was 60 percent. The maximum extent of microscopic distal spread and adjusted distal spread in situ were 20 and 24 mm, respectively. CONCLUSIONS: Excising the mesorectum with fascia propria circumferentially intact is essential for rectal surgery. The optimal distal clearance margin for the rectal wall as well as the mesorectum in situ can be reduced to 3 cm with a right angle.     

Anatomic Study of Lateral Pelvic Lymph Nodes: Implications in the Treatment of Rectal Cancer

PURPOSE Lateral pelvic lymphadenectomy remains a controversial issue in rectal cancer surgery. Beyond clinical results, disagreement includes surgical anatomy aspects and definitions, as wells as lack of information about location, groups, and number of lymph nodes, all of which makes comparison of results difficult. We performed a systematic examination of the number and distribution of lateral pelvic lymph nodes using cadaveric dissection.METHODS Sixteen formalin-fixed cadavers were dissected (14 males). Dissection fields were divided according to the three surgical groups of pelvic wall lymph nodes: presacral, obturator, and hypogastric. Number and site of excised lymph nodes was recorded, noting neurovascular relationships.RESULTS A total of 458 lymph nodes were found, with a mean of 28.6 nodes per pelvis (range, 16-46). Lymph node size ranged from 2 to 13 mm. The highest number of lymph nodes was found in the obturator fossa group (mean, 7; range, 2-18). Hypogastric lymph nodes were found lying predominantly above the inferior hypogastric nerve plexus but reaching the deep pelvic veins.CONCLUSIONS The mean number of lymph nodes found in lateral pelvic wall compartments was 28.6 per specimen. The group containing most lymph nodes lies in the obturator fossa. Complete excision of hypogastric lymph nodes demands a deep pelvic dissection of neurovascular structures.     

Pathological study of distal mesorectal cancer spread to determine a proper distal resection margin

AIM: Local recurrence after curative surgical resection for rectal cancer remains a major problem. Several studies have shown that incomplete removal of cancer deposits in the distal mesorectum contributes a great share to this dismal result. Clinicopathologic examination of distal mesorectum in lower rectal cancer was performed in the present study to assess the incidence and extent of distal mesorectal spread and to determine an optimal distal resection margin in sphincter-saving procedure. METHODS: We prospectively examined sepecimens from 45 patients with lower rectal cancer who underwent curative surgery. Large-mount sections were performed to microscopically observe the distal mesorectal spread and to measure the extent of distal spread. Tissue shrinkage ratio was also considered. Patients with involvement in the distal mesorectum were compared with those without involvement with regard to Clinicopathologic features. RESULTS: Mesorectal cancer spread was observed in 21 patients (46.7%), 8 of them (17.8%) had distal mesorectal spread. Overall, distal intramural and/or mesorectal spreads were observed in 10 patients (22.2%) and the maximum extent of distal spread in situ was 12 mm and 36 mm respectively. Eight patients with distal mesorectal spread showed a significantly higher rate of lymph node metastasis compared with the other 37 patients without distal mesorectal spread (P=0.043). CONCLUSION: Distal mesorectal spread invariably occurs in advanced rectal cancer and has a significant relationship with lymph node metastasis. Distal resection margin of 1.5 cm for the rectal wall and 4 cm for the distal mesorectum is proper to those patients who are arranged to receive operation with a curative sphincter-saving procedure for lower rectal cancer.     

Distal intramural spread in adenocarcinoma of the lower third of the rectum treated with total rectal resection and coloanal anastomosis

PURPOSE: This study was designed to evaluate the frequency of microscopic distal intramural spread in rectal adenocarcinoma and its correlation to other histopathologic prognostic factors. METHODS: We examined 55 patients with adenocarcinomas of the lower one-third of the rectum and measured the extent of distal intramural spread in the submucosa and/or muscular layer in comparison with Dukes Stage, diameter of tumor, distance of distal margin of resection from tumor, depth of infiltration into perirectal adipose tissue, nodal status, neoplastic infiltration of lymphatic vessels, blood vessels, and nervous branches. RESULTS: Distal intramural spread was found in 40 percent of patients, 77 percent of whom had advanced tumors with nodal metastases. Distal intramural spread appeared to be strictly related to tumor size (superior to 40 mm), infiltration of the perirectal adipose tissue, multiple positive lymph nodes, presence of neoplastic emboli in the intramural lymphatic vessels, and neoplastic invasion of the nervous branches. Local recurrence occurred in one Dukes Stage B patient with a positive distal margin of resection and in four patients with a negative distal margin of resection: three Dukes Stage C and one Dukes Stage B patients with neoplastic involvement of the circumferential margin of resection of the mesorectum. CONCLUSION: These preliminary data suggest that distal intramural spread may carry little importance in determining local recurrence of rectal adenocarcinoma.Supported by Associazione Italiana Ricerca sul Cancro.     

Distribution of metastatic lymph nodes in colorectal cancer by the modified clearing method

PURPOSE: The aim of this study was to clarify the distribution of lymph node metastasis in colorectal cancer. We also examined the relationship between the primary tumor (T) and the regional node (N) categories of the TNM (primary tumor, regional nodes, metastasis) classification. METHOD: Lymph nodes of surgical specimens in 311 consecutive patients with colorectal cancer were studied using the modified clearing method. RESULTS: Lymph node metastasis was seen in 59.2 percent of the total cases. The upward metastasis rate was 30.7 percent. In the longitudinal spread, most of the lymph node metastasis was seen within 10 cm. On the oral side in rectal cancer, there was no metastasis beyond 4 cm. The lateral metastasis rate in rectal cancer was 8.8 percent and in the lower rectum, the rate of cancer within 6 cm from the anal verge or beyond pT3 was much higher. CONCLUSION: In the TNM classification, there was no significant difference between colon and rectal cancer except pT1 with rectal cancer. In the lower rectal cancer within 6 cm from the anal verge or beyond pT3, there is a high risk of lateral metastasis, and lateral lymph node dissection or radiation therapy should be performed.     

Lymph node involvement and tumor depth in rectal cancers

BACKGROUND: Superficial rectal tumors are said to involve regional lymph nodes rarely. This presumption must be proven beyond any doubt if less radical surgery is to be offered for such patients. PATIENTS AND METHODS: Eight hundred five cases (467 males; median age, 64 (range, 19–97) years) of rectal cancer were reviewed. RESULTS: Lymph node positivity, number of lymph nodes involved, lymphatic vessel, and venous and perineural invasion were significantly increased with increasing depth of invasion of tumor through the bowel wall in univariate analysis. The percentage of lymph node involvement at each tumor depth was as follows: T1, 5.7 percent; T2, 19.6 percent; T3, 65.7 percent; T4, 78.8 percent. Overall lymph node involvement was 59 percent. For patients younger than 45 years of age, the percentage of lymph node involvement was 33.3, 30, 69.3, and 83.3 percent compared with 3.1, 8.4, 64.2, and 78.8 percent for patients aged 45 years or above for T1, T2, T3, and T4, respectively. CONCLUSION: Increased depths of tumor penetration beyond T1 and age less than 45 years have an excessive incidence of lymph node positivity. The finding of lymphatic vessel invasion on biopsy is highly indicative of lymph node metastasis.     

Distribution of lymph nodes in the mesorectum: how deep is TME necessary?

BACKGROUND: Standardization of total mesorectal excision (TME) had a great impact on decreasing local recurrence rates for the treatment of rectal cancer. However, exact numbers and distribution of lymph nodes (LN) along the mesorectum remains controversial with some studies suggesting that few LNs are present in the distal third of the mesorectum. METHODS: Eighteen fresh cadavers without a history of rectal cancer were studied. The rectum was removed by TME and then was divided into right lateral, posterior and left lateral sides, which were further subdivided into 3 levels (upper, middle and lower). A pathologist determined the number and sizes of the LNs in each of the nine areas, b linded to their anatomical origin. RESULTS: Overall, the mesorectum had a mean of 5.7 LNs (SD=3.7) and on average each LN had a maximum diameter of 3.0 mm (SD=2.7). There was no association between the mean number or size of LNs with gender, BMI, or age. There was a significantly higher prevalence of LNs in the posterior location (2.8 per mesorectum) than in the two lateral locations (0.8 and 1.2 per mesorectum; p=0.02). The distribution of LNs in the three levels of the rectum was not significant. CONCLUSIONS: The distribution of LNs reinforces the fact that TME should always include the distal third of the mesorectum. Care must be taken to not violate the posterior aspect of the mesorectum.     

Injection of methylene blue solution into the inferior mesenteric artery of resected rectal specimens for rectal cancer as a method for increasing the lymph node harvest

Background

The aim of the present study was to determine whether the injection of methylene blue solution into the inferior mesenteric artery could improve the lymph node harvest in rectal specimens of rectal cancer patients treated with rectal resection with total mesorectal excision.

Methods

The study group consisted of 20 randomly selected fresh rectal specimens from patients with stages I-III rectal cancer treated at the Surgery Clinic at the Institute of Oncology of Vilnius University during the period from February 2008 to December 2010, and 20 specimens were selected under the same conditions to serve as the control group. The patients underwent conventional rectal resection with total mesorectal excision and coloanal anastomosis for low rectal cancer performed by the same surgeon, did not receive preoperative radiotherapy and had no distant metastases. After the removal of the specimen, 30?ml of 0.5% methylene blue solution was injected into the inferior mesenteric artery of the specimens in the study group (methylene blue group). The specimens from both the methylene blue and control groups were examined using the standards established by the Lithuanian National Centre of Pathology. The pathologist was not required to make any special macroscopic preparations. A retrospective analysis of clinical and histopathological records was performed.

Results

Comparison of the mean lymph node harvest showed a significant difference between methylene blue and control groups with average lymph node numbers per specimen of 18?±?5 and 14?±?6, respectively (p?=?0.025). The specimens from 12 of the 20 patients in the methylene blue group and the specimens from 7 of the 20 patients from the control group had positive nodes.

Conclusions

Injecting methylene blue solution into the inferior mesenteric artery is an efficient and simple method for improving the lymph node harvest in the histopathological examination of rectal specimens of rectal cancer patients treated with rectal resection with total mesorectal excision.