***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background and aims : There is a need for objective easily determined pathological prognostic parameters in Dukes ' B colon carcinoma to allow selection of such patients for further treatment as the role of adjuvant chemotherapy for these patients remains unclear . This study was initiated to assess the influence of pathological factors on prognosis in an unselected prospect i ve series of Dukes ' B colonic cancer . Methods : The Gloucester Colorectal Cancer study , established in 1988 , recruited more than 1000 cases . Meticulous pathological assessment of the 268 Dukes ' B colonic cancer resections in this series included evaluation of all pathological factors that could influence staging and prognosis . All patients entered a comprehensive follow up system . Results : Four pathologically determined factors — peritoneal involvement , venous spread ( both submucosal and extramural ) , spread to involve a surgical margin , and perforation through the tumour — were independent prognostic factors in multivariate analysis . Combining these four factors into a simple cumulative scoring system generated clinical ly useful prognostic groups . Conclusions : The cumulative prognostic index allows apportionment of patients with Dukes ' B colon cancer into defined prognostic groups , which in turn could allow more objective selection of patients for adjuvant therapy , especially as part of clinical trials Objective : To examine the clinical utility of improved detection of  venous invasion  ( VI ) in patients undergoing potentially curative resection of colorectal cancer . Background : VI is a feature of colorectal cancer ( CRC ) progression . Elastica staining can be used to improve detection of VI and correspondingly its prediction of patient survival . Methods : A single-center , observational study of pathology variables , including detection of VI by staining for elastica , using 631 stage I to III CRC specimens , collected from 1997 to 2009 ( 176 analyzed retrospectively and 455 analyzed prospect ively ) , was performed . Results : VI was detected in 56 % of patients with CRC . Over a median follow-up period of 73 months , 238 patients died ( 134 from cancer ) . On multivariate analysis , VI by elastica staining was associated with a shorter survival duration , independent of other pathology features , in all cases [ hazard ratio ( HR ) = 3.94 , 95 % confidence interval ( CI ) : 2.33–6.65 , P < 0.001 ] and in node-negative cases ( HR = 3.55 , 95 % CI : 1.81–6.97 ; P < 0.001 ) . In the absence of elastica-detected VI , with the exception of T stage , no other pathology features were associated with survival time . Therefore , the combination of T stage and  VI ( TVI ) on survival was examined . Five-year cancer mortality could be stratified between 100 % and 54 % for patients with node-negative tumors and between 100 % and 33 % for patients with node-positive tumors . In all cases , the TVI had similar predictive value as that of T stage and node status ( TNM ) . In node-negative disease , TVI had superior predictive value . Conclusions : The results of the present study have prompted the development of a novel tumor staging system based on TVI . The TVI has clinical utility , especially in node-negative disease , in predicting outcome following curative resection for CRC Colorectal cancer is a common malignancy and a leading cause of cancer related death . Cancer staging following resection is key to determining any adjuvant therapy in those patients with high risk disease . In colorectal cancer , tumour stage and lymph node stage are the main pathological factors which have been considered to influence outcome . Increasing emphasis is now being placed on other factors , especially the presence of extramural venous invasion ( EMVI ) . It is important to underst and the relationship of EMVI with other pathological factors and to confirm that in an individual centre that EMVI is being detected at an appropriate rate and is of prognostic significance . This comprehensive study assesses the reporting and prognostic significance of EMVI in a single centre , using prospect ively collected data from histopathology reports of a cohort of 2405 patients who underwent surgery for colorectal cancer over a nine year period . Overall , EMVI was reported in 27.9 % of colorectal cancer excision specimens . In tumours ( n = 1928 ) that had not received neoadjuvant therapy , the presence of EMVI varied significantly depending on tumour site ( χ2 = 12.03 , p<0.005 ) , tumour stage ( χ2 = 268.188 , p<0.001 ) , lymph node stage ( χ2 = 294.368 , p<0.001 ) and Dukes ’ stage ( χ2 = 253.753 , p<0.001 ) . Multivariate analysis confirmed EMVI as a significant independent prognostic indicator ( p<0.001 ) . In conclusion , the presence of EMVI as an independent prognostic indicator is shown and is related to other pathological and prognostic factors . This study emphasises the requirement for the accurate identification of EMVI in colorectal cancer excision specimens and also underst and ing the relationship of EMVI with other prognostic factors BACKGROUND : Extramural venous invasion is a known independent predictor of poor prognosis after resection of colorectal adenocarcinoma , but the prognostic value of mural venous invasion alone and the association between venous invasion and prognosis within tumor stages has received little research attention . OBJECTIVE : This study aim ed to determine whether associations between mural and extramural venous invasion and outcome differ among tumor stages after adjustment for other factors known to influence prognosis . DESIGN : This study is a retrospective analysis of prospect ively collected data . SETTING S : Data were drawn from a registry of 3040 consecutive patients undergoing resection between 1980 and 2005 under the care of specialist surgeons in a tertiary referral public hospital and an affiliated private hospital . A st and ardized protocol was used for the pathological assessment of specimens . MAIN OUTCOME MEASURES : The primary outcomes measured were overall survival , cancer-specific survival , and recurrence . RESULTS : There was no significant association between venous invasion and survival in stages A ( n = 544 ) or B ( n = 1078 ) . In stage C ( n = 899 ) , overall survival time was significantly shorter in patients with mural invasion alone or extramural invasion ( both p < 0.001 ) than in those without invasion , and this persisted after adjustment for other prognostic variables . Equivalent bivariate associations were found in stage D , but only the effect of extramural invasion persisted after adjustment . LIMITATIONS : Our findings arise from the experience of a single surgical group and may not be generalizable to other setting s. Only hematoxylin and eosin staining was used . CONCLUSIONS : The association between venous invasion and prognosis was stage specific . Both mural venous invasion alone and extramural venous invasion independently predicted overall survival in patients with stage C tumors , but not in patients with stages A , B , or D tumors . Although mural invasion alone was rare , the separate reporting of both mural and extramural invasion in patients with stage C tumor is informative and desirable We performed a long-term prospect i ve study on venous invasion of colorectal cancer . The degree of venous invasion was divided into four stages ( V0 through V3 ) . Venous invasion was classified into three types by location ( Vx , Vy , and Vz ) . Hepatic metastasis occurred in 27 % , 33 % , and 20 % of patients with V2 , V3 , and Vz tumors , respectively . Local recurrence occurred in 33 % and 15 % of the V3 and Vz groups , respectively . However , there were no significant differences among the groups in terms of the rate of pulmonary metastasis . The 6-year survival rate for Dukes ' stage B tumors was 94 % , 88 % , and 74 % in the V0 , V1 , and V2 groups , respectively . There was a significant difference in the survival rate between patients with V0 tumors and V2 and V3 tumors . However , no significant difference was noted in the location . In Dukes ' stage C tumors , on the other h and , the survival rate was 77 % , 56 % , and 44 % in the V1 , V2 , and V3 groups , respectively . Also , it was 85 % , 73 % , and 45 % in Vx , Vy , and Vz cases , respectively . Significant differences were noted between V1 and V3 ( or V2 ) , and between Vz and Vx ( or Vy ) . It appears that the degree and location of venous invasion influence not only hepatic metastasis , local recurrence , and survival rates but also have prognostic value 
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In conclusion , despite the limited number of studies , there is a clear association with outcome in the presence of IMVI .