Guidelines for Colo rectal resection: Margins and lymph nodes
Posted May 22 2009 10:40pm
Optimization of Pathological Quality Performance in Radical Surgery for Colon and Rectal Cancer: Margins and Lymph Nodes Guideline Recommendations : Cancer Care Ontario,Canada
Question: What is the recommended approach to processing and reporting the resected specimen, including specimen marking in the operating room, as well as processing and reporting requirements in the pathology laboratory? Answer: Proximal and Distal Margins The surgeon should communicate with the pathologist regarding the orientation of the specimen. Proximal and distal margins should be sampled for histological examination. The distance of the tumour to the proximal and distal margins should be reported in the fresh state, if possible. Measurement in the fixed state must take into account the fact that shrinkage will have occurred; pinning the fresh specimen to a board, under tension, will produce less shrinkage. If the tumour is close to a margin, the distance between the tumour and the margin of concern should be reported as measured microscopically on the glass slide. Radial Margins The surgeon must clearly indicate to the pathologist areas with close contact to other organs or the abdominal wall. The pathologist should be aware of the retroperitoneal margin that exists in certain locations (e.g., proximal ascending colon and descending colon). The radial margins of the resected specimen should be inked and sectioned. The radial margin distance must be reported. The radial margin should be reported as positive if tumour is located 1 mm or less from the inked nonperitonealized surface of the specimen.
Margins of Resection: Rectum Technical Recommendations Technical recommendations are based on the Expert Panel consensus informed by the technical issues highlighted in four key papers in the field (2-5), as well as pathology studies identified in the recent literature search.
Proximal and Distal Margins Proximal and distal margins should be sampled for histological examination. Pathologists should pay close attention to mesorectal soft tissue, in addition to the mucosa, when assessing the distal margin. Circumferential Radial Margins All rectal cancer specimens should be assessed grossly by the pathologist using the method developed by Quirke . The mesorectal tissue that constitutes the CRM, including all non-peritonealized bare areas anteriorly and posteriorly, should be inked. The specimen should be fixed with the tumour segment unopened 5 cm above and below the proximal and distal edges of the tumour, respectively, and a gauze wick placed into the unopened segment to facilitate fixation. Following at least 48 hours of fixation, the segment with the tumour should be sliced into transverse sections. The relationship of the tumour to the CRM must be carefully assessed. The CRM distance must be reported. The CRM is positive if the tumour is located 1 mm or less from the margin; this includes tumour cells within a lymph node, vein, or nerve, as well as direct tumour extension. Note that tumours of the upper rectum have a peritonealized anterior surface and a non-peritonealized posterior radial margin similar to the ascending and descending colon.
Involvement of the serosa by tumour (pT4b) is not equivalent to involvement of the radial margin by tumour (although there are circumstances in which an advanced tumour has penetrated the serosa and is adherent to adjacent soft tissue). Documentation of serosal involvement by tumour requires careful gross and microscopic examination and may require extensive sampling and/or serial sectioning of sampled tissue blocks. Serosal penetration is defined as occurring when any of the following criteria are met: Free tumour cells are present on the serosal surface with underlying ulceration. Tumour is present at the serosal surface with an associated inflammatory reaction, mesothelial hyperplasia, and/or erosion or ulceration. The tumour is close to, but not at the serosal surface but there is an associated mesothelial inflammatory and/or hyperplastic reaction.
Serosal penetration is an independent prognostic variable and has a strong negative impact on prognosis. The frequency of distant metastasis is greater in cases with perforation of the visceral peritoneum compared to cases with direct invasion of adjacent organs or structures without perforation of the visceral peritoneum, and the median survival time following surgical resection for cure is shorter for patients with pT4b tumours compared to those with pT4a tumours (with or without distant metastasis).
Lymph Node Assessment
Technique of Lymph Node Examination Technical recommendations are based on Expert Panel consensus informed by four key papers in the field (2-5) and pathology studies identified in the recent literature search. Pericolic fat should be carefully examined using inspection and palpation. For colonic tumours, examination should occur after pericolic fat has been stripped off the colon and after any appropriate sections have been taken to evaluate the radial margin. In the case of rectal tumours, the cross-sectioned slices are examined for lymph nodes, taking care not to double count lymph nodes that might be present in more than one cross-sectional slice. All lymph nodes present must be examined histologically. Nodal examination must not stop once 12 nodes have been identified. It is particularly important to find small lymph nodes close to the underlying bowel wall. If less than 12 lymph nodes are found, consideration should be given to placing the fat into a lymph node highlighting solution. All grossly negative or equivocal lymph nodes must be submitted in their entirety. However, if a node is grossly positive, partial submission is acceptable.
Number of Lymph Nodes Assessed Technical Recommendations Technical recommendations are based on Expert Panel consensus informed by four key papers in the field (2-5) and pathology studies identified in the recent literature search. The pathology report should indicate the number of positive lymph nodes as well as the total number of nodes assessed. The number of lymph nodes involved by micrometastases (tumour deposits >0.2 mm but
<2.0 mm) and isolated tumour cells (ITCs) (single cells or clusters 0.2 mm or less) should be reported separately from typical (macro) metastases. In cases where there are typical (macro) metastases, micrometastases or ITCs do not change the pN stage. Micrometastases without typical (macro) metastases detected by routine histology are reported as pN1, whereas immunohistochemical detection is reported as pN0. The presence of ITCs does not change the pN classification. Note that special measures to detect micrometastases or ITCs (e.g. multiple tissue levels of paraffin blocks, immunohistochemistry [IHC], polymerase chain reaction [PCR]) are not recommended for the routine examination of regional lymph nodes. A tumour nodule in the pericolonic/perirectal fat without histologic evidence of residual lymph node tissue is classified as a lymph node replaced by tumour if the nodule has the form and smooth contour of a lymph node. If the nodule has an irregular contour, the nodule should be classified as a discontinuous extramural extension, pT3 (based on the AJCC/UICC TNM 6th edition).
RELATED GUIDELINES Practice Guideline Report #2-20-2: Laparoscopic Surgery for Cancer of the Colon, September 2005 Practice Guideline Report #2-9: Follow-up of Patients with Curatively Resected Colorectal Cancer, January 2004 Diagnostic Imaging Recommendations Report: Cross-sectional Imaging in Colorectal Cancer, April 2006 Multidisciplinary Care Conference Standards, June 2006 Evidence-Based Series: #2-29: Adjuvant Systemic Chemotherapy for Stage II and III Colon Cancer Following Complete Resection, April 2008 Evidence-Based Series #2-4: Preoperative or Postoperative Therapy for the Management of Patients with Stage II or III Rectal Cancer [In progress]