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Table 2. Pathological TNM classification according to the 5 th edition of TNM - pTNM5.TTXT0TisT1T2T3T4NNXN0N1N2MMXM0M1Primary tumorprimary tumor cannot be assessedno evidence of primary tumorcarcinoma in situ: intraepithelial or invasion of lamina propriatumor invades submucosatumor invades muscularis propriatumor invades through muscularis propria into subserosa or into non-peritonealized periodicor rectal tissuetumor directly invades other organs or structures and/or perforates visceral peritoneumRegional lymph nodesregional lymph nodes cannot be assessedno regional lymph node metastasismetastasis in 1 to 3 regional lymph nodesmetastasis in 4 or more regional lymph nodesDistant metastasesdistant metastasis cannot be assessedno distant metastasisdistant metastasisined lymph nodes must be included. Data are insufficientto recommend the routine use of tissuelevels or special/ancillary techniques. 21 Importantto know is that many involved lymph nodes aresmall, sometimes only a few millimeters in size. 29This can explain the poor correlation with predictionof involved lymph nodes preoperatively byMRI. 30 If the pathologists are using the 6 th editionof TNM, his correlation may even be worse, owingto the classification of all round extramural tumordeposits as completely involved lymph nodes withoutresidual lymphoid tissue. 23 Extramural tumordeposits with an irregular contour are consideredas vascular invasion. In the 5 th edition of TNM,extramural deposits that are not obviously withinlymph nodes are regarded as discontinuous extensionsof the main tumor if they measure 3 mm in diameter. 22 Whilst the evidence for thisdefinition is weak, it does at least have the advantageof being quantitative and, therefore, reproducibleand it may increase pathologist/radiologistagreement. 30 The UK and much of Scandinaviarefused to move to TNM6 as the evidence base isinadequate for the classification of lymph node andvenous invasion, and in addition, the interobservervariability is poor. 30 It has also been advocated bythe PROCARE working group to stick to the 3 mmrule of the TNM5 classification. 2The distance to the circumferential regression margin(CRM) must be measured. A positive CRM isdefined as tumor extension (either continuous ordiscontinuous) or the presence of a positive lymphnode
P R A C T I C E G U I D E L I N E SFigure 4. Slide of a large-area (giant) block, allowing tomeasure the distance of the tumor to the CRM (the resectionmargin is painted with india ink).used to indicate the presence of vascular or lymphaticinvasion. 22Distant metastasis is reported as M1 if confirmedat histological examination. Non-regional lymphnodes are classified as metastases and should be describedseparately. A positive cytological peritonealfluid is also classified as M1. 22Neoadjuvant radiochemotherapy changesThe pathologist should be informed about preoperativetreatment, as in case of neoadjuvant radiochemotherapy(ypTNM) it is advised to estimate tumorregression by means of a semiquantitative gradingsystem, e.g. the Dworak regression grade (Table 3),where regression of the primary tumor is semiquantitativelydetermined by the amount of viable tumorversus the amount of fibrosis, ranging from no evidenceof any treatment effect to a complete responsewith no viable tumor identified. 20 Regression gradingis important for prognosis with a complete responsehaving a better outcome than microscopic diseaseand the latter doing better than moderate, mild, orno regression. 20,30,32,33 Before concluding that there iscomplete response with no viable tumor identified,embedding of the whole suspicious area and the applicationof step sectioning is suggested. 20 To combinerigorous dissection with practicality, it is recommendedthat 5 initial blocks are taken from the siteof the tumor. If no tumor is present, the completesuspicious area should be embedded. If there is stillno tumor, then 3 levels should be cut through eachblock. If finally there is still no tumor found, then thepatient is reported as having a complete response. 34Pathological reporting of rectal cancer resectionspecimensUse of pathology report forms ensures the completenessand consistency of data reporting. This is notonly important for determination of individual patientprognosis and further treatment, but also forassessment of quality of rectal surgery, and the overallmanagement of the disease. Two pathological reportforms are proposed by the <strong>Belgian</strong> PROCAREworking group, one for PME, TME, or APR, anda second form for local (transanal) resection. Thelast updated version of the checklists can be downloadedfrom www.kankerregister.be (menu: procare/working) or www.registreducancer.be (menu: procare/working).The protocol for local resection specimensincludes the pathological subclassificationinto 3 levels of the depth of invasion in superficial(mucosal or submucosal) cancer (Table 4).ConclusionsTotal mesorectal excision (TME) became thestandard surgical treatment for rectal cancer, as itgreatly reduces local recurrences. 1,3 TME and a multidisciplinaryoncologic team approach have led tosignificant improvements in outcome of rectal cancertreatment. 1 Pathologists play a key role in thisprocess. Proper pathological assessment of the TMEspecimen provides important prognostic informationfor the oncologist and identifies patients thatrequire further therapy. 6,15TME resection specimens require a special pathologicalwork-up, as pathologists not only have to determinethe pathological stage of rectal cancer, butin addition they have to assess the completeness oftumor resection and the quality of the mesorectalexcision. 5,6 For this purpose it is important that theresection specimen is delivered unopened to the pathologist.5,6,8 Assessment of the quality of mesorectalexcision must be based on a macroscopic observationof the external surface as well as evaluation ofcross-sectional slides. 5,6 Careful macroscopic as wellas microscopic assessment of the distance of the tumorto the circumferential resection margin (CRM)is of high importance, as this is the most significantpredictor of local recurrence. 6,8-10 In patients witha negative CRM, incomplete mesorectal resectionleads to a higher recurrence rate and lower survival. 5For an adequate benefit of a multidisciplinary oncologicteam approach, it is necessary that all membersof the different medical disciplines of the teamhave sufficient background knowledge of imaging,257v o l . 3 i s s u e 6 - 2 0 0 9B E L G I A N J O U R N A L O F M E D I C A L O N C O L O G Y
Page 2 and 3: ABFigure 1. Anterior (A) and poster
Page 4 and 5: Table 1. Grading of the quality of
Page 8 and 9: Table 3. Dworak regression grade. 2

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