Lymphknotendissektion bei Karzinomen des unteren Gastrointestinaltraktes: Was ist evidenzbasiert?

Impact of Proximal Vascular Ligation on Survival of Patients with Colon Cancer

In an effort to optimize further the surgical management of colon cancer, many groups have advocated extended lymphadenectomy as a strategy to improve completeness of resection and lymph node harvest. This review evaluates lymphadenectomy according to the definitions for extent of lymph node dissection based on the guidelines provided by the Japanese Society of Cancer of the Colon and Rectum and the contemporary concepts of complete mesocolic excision and central vascular ligation. The proposed benefits of a D3 or central nodal dissection along root vessels in colon cancer is improving accuracy of lymph node evaluation and ensuring complete removal of lymph nodes that may harbor undetected tumor cells or other undefined immunologic processes important for metastases. Metastasis to central lymph nodes occurs in 1 to 8% of patients with colon cancer and is most commonly seen in T3 and T4 tumors. Although central lymph node metastasis is associated with decreased survival after resection, resection of the nodes, when present, may confer a survival benefit analogous to resection of metastasis at distant sites. Current data support a standardized anatomic approach to colonic resection with complete resection of the mesocolic envelope and ligation at least to the D2 level.

[Lymph node dissection after primary surgery and neoadjuvant radiochemotherapy of rectal cancer. Interim analysis of a multicenter prospective observational study (OCUM)]

INTRODUCTION

The OCUM trial (NCT01325649) aims to clarify whether low rates of local recurrence are also achieved when the indications for neoadjuvant radiochemotherapy are not based on the clinical TNM staging but on preoperative magnetic resonance imaging with measurement of the tumor distance to the circumferential resection margin. In this interim analysis the lymph node status in OCUM patients was investigated as a surrogate parameter for quality of surgery and histopathological work-up.

MATERIAL AND METHODS

Until now a total of 560 patients have been included in this study. Total mesorectal excision (TME) without pretreatment was undertaken in 338 patients (60.4 %) and neoadjuvant radiochemotherapy was administered in 222 (39.6 %) patients. The histological work-up was performed according to the guidelines of the German Association of Pathologists. Data are given as median values and ranges in brackets.

RESULTS

The lymph node yield was 24 (7-79) in 338 patients undergoing primary TME surgery without pretreatment, while 20 (3-56) lymph nodes were identified in patients after neoadjuvant radiochemotherapy (p = 0.001). A minimum of 12 lymph nodes were analyzed in 335 out of 338 patients (99.1 %) and in 209 out of 222 patients (94.1 %) following neoadjuvant radiochemotherapy (p = 0.001). Lymph node metastasis was identified (p = 0.362) in 116 out of 338 patients without pretreatment (34.3 %) and in 71 out of 222 patients after neoadjuvant radiochemotherapy (32.0 %). Patient age did not influence the number of identified lymph nodes or rate of lymph node metastasis.

CONCLUSION

In this trial the number of identified lymph nodes suggests that the quality of surgery and histopathological work-up were adequate compared to the standards defined by national guidelines. Neoadjuvant radiochemotherapy led to a reduced lymph node yield compared to surgery without pretreatment; however, this did not influence the rate of lymph node metastasis.

[Laparoscopic surgery for colon cancer: quality requirements for (extended) right hemicolectomy]

The current S3 guidelines on the surgical treatment of colorectal cancer note that with a suitable patient selection and expertise of the surgeon the same oncological results can be achieved laparoscopically as with the open procedure. This requires that the same quality requirements have to be provided for both methods. The most important quality parameters of right sided (extended) hemicolectomy are central ligation of the supplying arteries (ileocolic artery, right branch of the middle colic artery and middle colic artery) flush to the central origin of the vessel (superior mesenteric artery or middle colic artery) and the sharp dissection of the mesocolon without any preparation tears. The photographic documentation of the fresh surgical specimens for categorizing the preparation quality as well as to determine the pedicle of the vessel can capture this quality well and is also currently the best surrogate parameter to evaluate the oncological quality of the operation. At present, there are still considerable widespread deficits not only with the laparoscopic approach but also in open surgery which must be urgently fixed.

Extended lymphadenectomy in colon cancer is crucial

No one doubts that lymph node dissection in colon cancer is necessary, it is just the extent of that dissection that is still under debate. As the individual steps of an oncologic operation cannot be separated from each other, analysis of the significance of lymph node dissection alone is difficult. It has been proven that the T category is directly related to the number and central spread of lymph node metastases. Micrometastases and isolated tumor cells may be detected in lymph nodes by using special staining techniques; their presence may worsen prognosis significantly and approximate it to UICC stage III. The numbers of dissected lymph nodes and the ratio of involved versus dissected lymph nodes have been used as markers for quality of surgery and histopathological evaluation. Recent results underscore the importance of technique and extent of dissection. Dissection must be performed along the embryologic planes of the mesocolon and leave them intact. A high vascular tie with preservation of the central hypogastric nerves must be applied in order to achieve the best oncologic results while preserving quality of life. Extended lymphadenectomy is oncologically relevant only when it is combined with removal of the primary tumor with adequate longitudinal clearance, an intact complete mesocolon, and high vascular tie. It is part of a concept in which the tumor-bearing specimen is harvested as an enveloped package to minimize the risk of tumor cell spillage and local recurrence.

[Principles and technique of lymph node dissection in colorectal carcinoma]

Colorectal carcinoma is a common malignant tumor which shows a standard behavior for lymphogenic metastasis. Depending on the localization of the primary tumor the corresponding lymphatic area also has to be removed because lymph node metastases can already be present by every tumor even if there is no obvious intraoperative evidence. Lymphatic drainage is essentially oriented to the supplying arteries of the corresponding intestinal segment. The anatomy of arterial supply is individually variable and often deviates from the usual textbook presentation. In this review the oncological requirements of an adequate lymph node dissection in colorectal carcinoma are described with emphasis on the technical aspects to obtain an optimal specimen.