Tumour budding as prognostic factor in stage I/II colorectal carcinoma

Clinicopathological correlates and prognostic significance of maspin expression in 450 patients after potentially curative resection of node-positive colonic cancer

AIMS

The tumour suppressor maspin has been investigated for its association with conventional histopathological features in colorectal cancer and for its potential as an independent predictor of survival and response to adjuvant chemotherapy. The aim of this study was to examine associations between maspin expression, other histopathology and survival in a large consecutive series of patients after potentially curative resection of node-positive colonic adenocarcinoma.

METHODS AND RESULTS

Nuclear and cytoplasmic maspin expression in both superficial and deep parts of the tumour were assessed retrospectively by tissue microarray and immunohistochemistry in specimens from 450 patients whose other histopathology had been recorded in a prospective hospital registry of large bowel cancer resections from 1971 to 2001 with a minimum follow-up of 5 years. Among 13 clinicopathological features examined, the only associations that persisted across all four maspin assessments were stronger expression in right- than in left-sided tumours (P=0.001-0.011) and stronger expression in high-grade tumours (P<0.001-0.007). There was no significant association between intensity of maspin expression and overall survival.

CONCLUSIONS

In this large and thoroughly documented series of patients with clinicopathological stage C colonic tumour, maspin expression was correlated with few other conventional histopathology variables and was not a significant prognostic factor.

TNM staging system of colorectal carcinoma: a critical appraisal of challenging issues

CONTEXT

Colorectal cancer is the leading cause of morbidity and death among gastrointestinal tumors and ranks fourth after lung, breast, and ovarian cancers. Despite a continuous refinement of the T (tumor), N (node), and M (metastasis) staging system to express disease extent and define prognosis, and eventually to guide treatment, the outcome of patients with colorectal cancer may vary considerably even within the same tumor stage. Therefore, the need for new factors, either morphologic or molecular, that could more precisely stratify patients into different risk categories is clearly warranted.

OBJECTIVES

To present the state of the art with regard to the colorectal cancer staging system and to discuss confusing and/or challenging issues, including the assessment of peritoneal membrane involvement, vascular invasion, tumor deposits, and pathologic tumor response to neoadjuvant chemoradiotherapy.

DATA SOURCES

Literature review of relevant articles indexed in PubMed (US National Library of Medicine) and primary material from the authors' institutions.

CONCLUSIONS

Two emerging needs exist for the TNM system, namely, further stratification of patients with the same tumor stage and incorporation of nonanatomic factors, the latter including molecular and treatment factors. The identification and classification of morphologic features encountered in the pathologic examination of colorectal cancer specimens may be difficult and a source of subjective variability. Enhanced pathologic analysis, agreed-upon standard protocols, and standardization should improve the completeness and accuracy of pathology reports.

Shift from cytoplasmic to nuclear maspin expression correlates with shorter overall survival in node-negative colorectal cancer

Maspin has been characterized as a potent tumor suppressor in many in vitro and in vivo studies. In contrast, in stage III colon cancer, an association with shorter overall survival as well as sensitivity to chemotherapy was found for cases with nuclear maspin expression. Because 20% of node-negative colorectal cancer cases show a fatal clinical course, we hypothesized that immunohistochemical maspin expression could be of help to identify higher-risk cases. Therefore, we analyzed survival in a study employing 156 cases of stage I/II colorectal cases. Immunohistochemical cytoplasmic and/or nuclear maspin expression was found in 72% and 48% of the cases, respectively. Significant correlations between cytoplasmic expression and high tumor grade (P < .01) and between nuclear expression and tumor budding (P < .001) were shown. No differences concerning overall survival and immunohistochemical maspin expression were found when the complete collective was analyzed. However, evaluation of the pT3 cases revealed a highly significant worse mean overall survival of cases with a combination of nuclear expression and cytoplasmic loss of maspin compared to cases with the opposite expression pattern nuclear loss and cytoplasmic expression (mean overall survival 40 versus 63 months, respectively; P < .001). The other possible combinations (complete positive and complete negative) showed intermediate mean overall survival times with 54 and 49 months, respectively. Our findings suggest a compartment-dependent function of maspin in colorectal cancer, which can be useful in identifying stage II cases with a higher risk for fatal outcome with a possible benefit from adjuvant chemotherapy.

Tumor budding and survival after potentially curative resection of node-positive colon cancer

PURPOSE

The aim of this study was to investigate the relationship between tumor budding and other pathology features and overall survival after resection of clinicopathological stage III colon cancer.

METHODS

The number of buds and other histopathological features were assessed in 477 patients who were operated on between 1971 and 2001, with follow-up to December 2006. Overall survival was analyzed using the Kaplan-Meier method and Cox regression.

RESULTS

The number of buds was dichotomized as low (0 to 8) vs high (>or=9). High budding was more common in men, in high-grade tumors, in the presence of venous invasion, and where the tumor had involved a free serosal surface, but budding was not associated with 8 other clinical and pathological features. The 5-year survival rate for patients with 0 to 8 buds was 51.0% (95% confidence interval, 44.9-55.1), whereas that for patients with 9 or more buds was 33.9% (95% confidence interval, 25.2-42.8). This association, however, disappeared after adjustment for other variables independently associated with survival (hazard ratio, 1.2; 95% confidence interval, 0.94-1.54; P = .139).

CONCLUSION

In stage III colon cancer, tumor budding did not provide additional independent prognostic information beyond that given by routine pathology reporting.

ABCG5-positivity in tumor buds is an indicator of poor prognosis in node-negative colorectal cancer patients

AIM: To analyze the expression of 8 putative cancer stem cell (CSC) markers within colorectal cancer tumor buds and to determine their prognostic impact in patients with this disease.

METHODS: Immunohistochemistry was performed on 101 colorectal cancer resections for CK22 (to identify tumor buds) as well as CD133, CD166, CD24, CD44s, CD90, EpCAM, ALDH1, and ABCG5, and their expression within tumor buds was evaluated.

RESULTS: CD90, CD44s, and CD133 expression in tumor buds was found in less than 5% of all cases. ALDH1, CD24, CD166 were expressed in 16.5%, 16.2%, and 34% cases, respectively, while ABCG5 and EpCAM expression was more frequent and found in 35% and 69% of cases, respectively. Of the 8 markers studied, EpCAM and ABCG5 positivity in tumor buds were significantly associated with poor prognosis (P = 0.023, P = 0.038, respectively) in multivariable analysis with pT and pN classification [P = 0.048; hazard ratio (HR): 2.64; 95% CI: 1.0-6.9, for EpCAM and P = 0.029; HR: 2.22; 95% CI: 1.0-4.5, for ABCG5]. Poor survival time was particularly striking for lymph node-negative patients with ABCG5-positive buds (P < 0.001).

CONCLUSION: Expression of putative stem cell markers EpCAM and ABCG5 within the tumor buds of colorectal cancer are frequently noted and are associated with poor prognosis.

Invasive front of colorectal cancer: Dynamic interface of pro-/anti-tumor factors

Tumor-host interaction at the invasive front of colorectal cancer represents a critical interface encompassing a dynamic process of de-differentiation of colorectal carcinoma cells known as epithelial mesenchymal transition (EMT). EMT can be identified histologically by the presence of “tumor budding”, a feature which can be highly specific for tumors showing an infiltrating tumor growth pattern. Importantly, tumor budding and tumor border configuration have generated considerable interest as additional prognostic factors and are also recognized as such by the International Union Against Cancer. Evidence seems to suggest that the presence of tumor budding or an infiltrating growth pattern is inversely correlated with the presence of immune and inflammatory responses at the invasive tumor front. In fact, several tumor-associated antigens such as CD3, CD4, CD8, CD20, Granzyme B, FOXP3 and other immunological or inflammatory cell types have been identified as potentially prognostic in patients with this disease. Evidence seems to suggest that the balance between pro-tumor (including budding and infiltrating growth pattern) and anti-tumor (immune response or certain inflammatory cell types) factors at the invasive front of colorectal cancer may be decisive in determining tumor progression and the clinical outcome of patients with colorectal cancer. On one hand, the infiltrating tumor border configuration and tumor budding promote progression and dissemination of tumor cells by penetrating the vascular and lymphatic vessels. On the other, the host attempts to fend off this attack by mounting an immune response to protect vascular and lymphatic channels from invasion by tumor buds. Whereas standard pathology reporting of breast and prostate cancer involves additional prognostic features, such as the BRE and Gleason scores, the ratio of pro- and anti-tumor factors could be a promising approach for the future development of a prognostic score for patients with colorectal cancer which could complement tumor node metastasis staging to improve the clinical management of patients with this disease.

Evaluation of venous invasion by Elastica van Gieson stain and tumor budding predicts local and distant metastases in patients with T1 stage colorectal cancer

Evaluation of pathologic predictors of metastases in T1 stage colorectal cancer may be difficult with hematoxylin and eosin (HE) staining alone. The aim of this study was to clarify the role of pathologic predictors by using immunohistochemical staining and Elastica van Gieson (EVG) staining. One hundred and twenty-four patients who underwent bowel resection for single T1 stage colorectal cancer from 1990 to 2004 in 1 institution were studied. D2-40, EVG staining, and CAM5.2 were used to detect lymphatic invasion, venous invasion, and tumor budding, respectively. These 3 factors were separately evaluated based on HE staining. Histology was reviewed by 1 pathologist. Lymph node metastases in the surgical specimen were the standard reference, and distant metastases were identified by periodic computed tomography for 2 years or more after surgery. A logistic regression model was applied to analyze risk factors for lymph node metastases and a Cox regression model for distant metastases. In predicting lymph node metastases, univariate analysis demonstrated significance for all predictors except venous invasion by HE staining. Multivariate analysis showed that venous invasion by EVG and tumor budding by HE showed significance as predictors. In predicting distant metastases, univariate analysis showed significance for lymphatic invasion shown by D2-40, tumor budding shown by CAM5.2 and HE, and lymph node metastases. Multivariate analysis showed only venous invasion by EVG stain as being significantly associated with distant metastases (P=0.001). In conclusion, venous invasion evaluated shown by EVG staining is a useful pathologic predictor for metastases in T1 stage colorectal cancer.

Prognostic significance of CXCL12 expression in patients with colorectal carcinoma

The present study investigated the protein expression level of CXCL12 in colorectal cancer and aimed to elucidate its association with prognosis. CXCL12 positivity in 50% or more of tumor cells was defined as high expression and that in less than 50% of the tumor cells as low expression. CXCL12+ tumor budding at the invasive front was divided into 2 grades: high with 10 or more budding foci per x200 field of view and low grade with fewer than 10 budding foci. Patients with high expression (72.7%) and high grade CXCL12+ tumor budding (43.0%) had significantly shorter survival than patients with low expression (P = .014) and low grade (P = .003), respectively. Patients with a combination of high expression and high grade had the worst outcome (P < .001). Our study demonstrated that CXCL12 expression in colorectal cancer cells and at sites of budding were significant prognostic factors. Furthermore, together with lymph node metastasis, a combination of both expression patterns was a more powerful independent prognostic factor.

Tumor budding is a strong and reproducible prognostic marker in T3N0 colorectal cancer

BACKGROUND

Tumor budding along the advancing front of colorectal adenocarcinoma is an early event in the metastatic process. A reproducible, prognostic budding scoring system based on outcomes in early stage colorectal cancer has not been established.

DESIGN

One hundred twenty-eight T3N0M0 colorectal carcinoma patients with known outcome were identified. Tumor budding was defined as isolated tumor cells or clusters of <5 cells at the invasive tumor front. Tumor bud counts were generated in 5 regions at 200x by 2 pathologists (conventional bud count method). The median bud count per case was used to divide cases into low (median=0) and high budding (median > or =1) groups. Forty cases were reevaluated to assess reproducibility using the conventional and a novel rapid bud count method.

RESULTS

Fifty-seven (45%) carcinomas had high and 71 (55%) had low budding scores. High budding was associated with an infiltrative growth pattern (P<0.0001) and lymphovascular invasion (P=0.005). Five-year cancer-specific survival was significantly poorer in high compared with low budding groups: 63% versus 91%, respectively, P<0.0001. Multivariate analysis demonstrated tumor budding to be independently prognostic (hazard ratio=4.76, P<0.001). Interobserver agreement was at least equivalent comparing the conventional to the rapid bud count methods: 87.5% agreement (kappa=0.75) versus 92.5% agreement (kappa=0.85), respectively.

CONCLUSIONS

Tumor budding is a strong, reproducible, and independent prognostic marker of outcome that is easily assessed on hematoxylin and eosin slides. This may be useful for identifying the subset of T3N0M0 patients at high risk of recurrence who may benefit from adjuvant therapy.

Colorectal carcinoma: selected issues in pathologic examination and staging and determination of prognostic factors

CONTEXT

Colorectal carcinoma is one of the most common types of cancer in Western countries and is consistently ranked among the top 3 causes of cancer-related deaths, with approximately 150 000 new cases in the United States and 55 000 deaths in 2006. The pathologist's assessment of tumor stage and stage-independent morphologic features, such as vascular/lymphatic invasion, influences treatment strategies for the individual patient, such as the decision to offer adjuvant therapy after surgery. However, although the pathologist influences clinical care in colorectal cancer, certain aspects of staging and evaluation of prognostic factors remain challenging and confusing.

OBJECTIVES

To present the currently used colorectal cancer staging system; to address challenging areas in pathologic staging, including T category considerations and recommendations for the minimum number of lymph nodes sampled; and to discuss assessment of selected stage-independent prognostic factors, such as vascular/ lymphatic invasion.

DATA SOURCES

This review is based on the current staging manual from the American Joint Committee on Cancer, the College of American Pathologists Protocol for Examination of Specimens From Patients With Primary Carcinomas of the Colon and Rectum, and selected articles pertaining to colorectal carcinoma staging and prognostic factors accessible through Ovid Medline (National Library of Medicine, Bethesda, Md).

CONCLUSIONS

Proper assessment of pathologic staging for colorectal cancer and of morphologic prognostic factors requires a thorough understanding of staging guidelines and careful specimen dissection and sampling.

Pathological predictors for lymph node metastasis in T1 colorectal cancer

PURPOSE

To clarify pathological predictor for lymph node metastasis in T1 colorectal cancer.

METHODS

One hundred and sixty-four patients who underwent surgery for single T1 colorectal cancer were reviewed. The pathological differentiations of non-well differentiation, invasion depth (> or =2 000 microm), lymphatic channel involvement, venous invasion, and tumor budding were selected as candidate predictors. Tumor budding was estimated according to the definition proposed by Ueno et al. (Gastroenterology 2004; 127:385-394). The lymph node status was set for the endpoint. Logistic regression model was applied to analyze the predictors.

RESULTS

Lymph node involvement was observed in 9.8%. The positive rates were 13.4% for the pathological differentiations of non-well differentiation, 51.8% for invasion depth (> or =2 000 microm), 6.1% for lymphatic channel involvement, 8.5% for venous invasion, and 14.6% for tumor budding. The pathological differentiations of non-well differentiation (P < 0.001) and tumor budding (P = 0.002) were significantly associated with lymph node metastasis in multivariate analysis. When either two significant factors was adopted for the prediction of the lymph node metastasis, the sensitivity, specificity, positive predictive value, and negative predictive value were 94%, 82%, 36%, and 99%, respectively.

CONCLUSION

The pathological differentiations of non-well differentiation and tumor budding are useful predictors for lymph node metastasis in T1 colorectal cancer.

Disturbed expression of E-cadherin, beta-catenin and tight junction proteins in colon carcinoma is unrelated to growth pattern and genetic polymorphisms

Adhesion proteins are responsible for the structural integrity of epithelial tissue and in tumors this integrity is often lost, resulting in a disorganization of the tissue. In the present study the complexity of the invasive front of colon carcinomas was correlated with cell adhesion protein expression and with polymorphisms in their genes. A complexity index was constructed from 32 colon carcinomas using computer-assisted morphometry estimating fractal dimension and tumor cell clusters followed by tree analysis. Immunohistochemical staining of beta-catenin, E-cadherin, occludin and claudin 2 was used for assessment of protein expression. Genetic screening of tissue from the tumor invasion front with laser microdissection was performed using SSCP and DNA sequencing. Adhesion protein distribution was significantly disturbed in most carcinomas. A single mutation in the gene of beta-catenin was found but there was no correlation between protein expression and genetic polymorphism. Nor was there any correlation between the complexity of the invasive border and protein distribution or genetic alterations. The results indicate that the complexity of colon carcinoma invasion is not dependent on genetic derangements in the genes of adhesion proteins or the protein distribution. Rather, aberrations in the function of other proteins related to the adhesive proteins could be responsible.

Role of desmoplasia in recurrence of stage II colorectal cancer within five years after surgery and therapeutic implication

BACKGROUND

Colorectal cancer (CRC) metastasis is enhanced in patients with venous embolization increasing the risk of recurrence and therefore mortality rate. Several evidences indicate that stage II patients have an abrupt recurrence within five years from surgery. This fact, led us to investigate the role played by different histological variables on CRC invasiveness.

AIM

To demonstrate if quantitative and qualitative desmoplastic response and lymphocytic infiltration are prognostic factor involved in the recurrence of CRC within five years from surgery, considering possible clinical and therapeutical implications.

METHODS

Thirty-four patients with CRC underwent colectomy and the UICC-TNM classification was applied for disease staging. Histological variables were semi-quantitatively evaluated. Qualitative evaluation of desmoplasia was obtained with the hematoxillin-eosin method.

RESULTS

Survival rate arose 88% at stage II, at five years of follow-up, and the 12% not treated with adjuvant chemotherapy developed metastasis. Desmoplasia is strongly associated with venous neoplastic invasiveness (OR: 21.93; 95%CI: 1.012-475.26, p = 0.02), and therefore, with mortality rate (OR: 14.33; 95%CI: 0.67-304, p = 0.04). Moreover, mortality rate was significantly higher in patients with immature desmoplasia compare to mature stromal tissue (OR: 15.61, 95%CI: 0.69-343.38, p = 0.04).

CONCLUSIONS

These observations should prompt a future evaluation of desmoplasia to extent more suitably the use of adjuvant chemotherapy in II stage patients. Further clinical trials are needed to determine if these findings will be able to reduce mortality rate, in stage II CRC patients.

High-degree tumor budding and podia-formation in sporadic colorectal carcinomas with K-ras gene mutations

In vitro ras activation enhances the epithelial-mesenchymal transition of colorectal carcinoma cells. But ras effects are known to be highly dependent on cell types and the tissue context. Therefore, this study was made to test the hypothesis that in clinical colorectal carcinoma specimens, aggressive invasion phenotypes, specifically tumor budding and podia formation, would correlate with K-ras gene mutations. In a series of 95 clinically sporadic primary colorectal carcinomas collected ad hoc, tumor budding and podia formation were counted using pan-cytokeratin immunohistochemistry, and K-ras gene mutations in codons 12 and 13 were determined. Consistent with the hypothesis, tumor budding and podia formation were observed to be significantly higher in the 32 (34.7%) of the tumors with K-ras gene mutations (29 mutations in codon 12, 3 in codon 13), and this correlation was observed independent of the patterns of invasion (expansive versus infiltrative). Microsatellite status, numbers of losses of heterozygosity, adenomatous polyposis coli and p53 gene mutations, and degree of promoter methylations (CIMP status) were not associated with K-ras gene mutations. Besides their effects on the tumor cell cycles, oncogenic K-ras gene mutations in colorectal carcinomas could be important for aggressive tumor invasion. This may be important in metastasizing disease and could provide a rationale for developing drugs that interrupt ras-signaling cascades.

Role of APAF-1, E-cadherin and peritumoral lymphocytic infiltration in tumour budding in colorectal cancer

Tumour budding or dedifferentiation at the invasive margin of colorectal cancer (CRC) is an important prognostic marker and linked mechanistically to dysregulation of Wnt pathway signalling. Since budding is observed in only 40% of CRCs, we hypothesized that Wnt pathway dysregulation may be a necessary but insufficient explanation for budding and that buds may be destroyed selectively by tumour immune mechanisms. Twenty potential markers of tumour budding were evaluated in tissue microarrays (TMAs) obtained from the main tumour body of 1164 DNA mismatch repair-proficient CRCs and the findings were correlated with tumour budding, lymphocytic infiltration and survival. Loss of expression of E-cadherin and APAF-1 were independent predictors of budding (sensitivity 70.3% and specificity 48.2% when one or the other was lost). Peritumoral lymphocytes (PTLs) were observed more frequently in CRCs with loss of either E-cadherin or APAF-1 that were budding-negative. PTLs and tumour-infiltrating lymphocytes (TILs) were strongly correlated. The absence of TILs increased the adverse prognostic impact of E-cadherin and APAF-1 loss. Co-occurrence of E-cadherin loss, APAF-1 loss and low TIL counts in CRCs was an independent prognostic factor. The findings were verified in whole tissue sections from 88 CRCs with known KRAS mutation status (which was not associated with budding). Loss of E-cadherin and APAF-1 within the main body of CRCs are independent predictors of tumour budding. The prognostic benefit of lymphocytic infiltration may be explained by the immune destruction of budding cells.

Correlation between liver metastasis of the colocalization of actin-related protein 2 and 3 complex and WAVE2 in colorectal carcinoma

Directed movement of normal cells occurs when actin-related protein 2 and 3 complex (Arp2/3 complex) triggers the actin polymerization that forms lamellipodia immediately after binding to WAVE2. In order to determine whether the same mechanism correlates with liver metastasis from colorectal cancer, paired mirror sections of 154 cancer specimens (29 cases with liver metastasis and 125 cases without liver metastasis in which T factor, gender, primary tumor site, and age at operation were matched) were examined immunohistochemically for the localization of Arp2 and WAVE2. Expression of both Arp2 and WAVE2 was detected in the same cancer cells in 55 (35.7%) of the 154 cases, but not detected in the normal colonic epithelial cells. Univariate analysis showed that the colocalization was significantly predictive of liver metastasis (risk ratio [RR] 8.760. Likewise, histological grade (RR 2.46), lymphatic invasion (RR 9.95), and tumor budding (RR 4.00) were significant predictors. Among these, colocalization and lymphatic invasion were shown to be independent risk factors by multivariate analysis. Another 59 colorectal specimens were examined for mRNA expression of Arp2 by real time polymerase chain reaction. High mRNA levels of Arp2, that in situ hybridization revealed to be expressed by the cancer cells, were significantly associated with liver metastasis. However, its effect was absorbed by the influence of risk of the colocalization that is closely related to high expression of Arp2. These results indicate that the colocalization of Arp2 and WAVE2 is an independent risk factor for liver metastasis of colorectal carcinoma.

Increased pontin expression in human colorectal cancer tissue

Wnt signaling plays a fundamental role in the control of cell proliferation and differentiation and is frequently deregulated in colorectal carcinoma leading to an enhanced expression of Wnt target genes. Pontin, a member of the AAA(+) superfamily, has previously been shown to interact with beta-catenin and to enhance TCF/beta-catenin-mediated transcription of Wnt target genes and thus may contribute to carcinogenesis. Here, we studied the expression of pontin in 34 patients with histologically proven colorectal cancer by immunohistochemistry on paraffin-embedded colorectal cancer samples using the monoclonal mouse anti-pontin (5G3-11) antibody. Cytoplasmic pontin staining of tumor cells was present in all cases and was stronger in 84.6% and equal in 15.4% of the cases compared with normal mucosa. In 50% of tumor specimens, an additional nuclear pontin staining pattern was noted with positivity ranging from 10% to 60% of the nuclei. Interestingly, all cases with nuclear pontin expression also revealed nuclear beta-catenin localization. Furthermore, pontin staining was stronger at the invasive margin and in tumor buds than in the tumor center in 41.2% and 37.9% of the cases, respectively. In this context, 66.7% and 64.7% of the cases with enhanced beta-catenin staining at the invasive margin and in tumor buds, respectively, also revealed stronger pontin expression. Analysis of pontin expression in 8 patients by Western blotting confirmed the histologic results. These data suggest that upregulation and nuclear localization of pontin together with beta-catenin may contribute to progression of colorectal carcinoma.

Tumour budding in colorectal carcinoma

The term tumour budding denotes that at the invasion front of colorectal adenocarcinomas tumour cells, singly or in small aggregates, become detached from the neoplastic glands. This morphological feature is increasingly being recognized as a strong and robust adverse prognostic factor. Biologically, tumour budding is closely related to the epithelial-mesenchymal transition. In this review the morphological features of tumour budding are discussed, as observed by the surgical pathologist reporting colorectal carcinoma resection specimens. The morphological features are put into context with the rapidly expanding knowledge of the epithelial-mesenchymal transition in general, and the molecular pathology of colorectal carcinoma in particular. Finally, a systematic analysis of the relevant published clinicopathological studies emphasizes the potential of tumour budding as a prognostic factor for routine surgical pathology.

Tumour budding in colorectal carcinoma

The term tumour budding denotes that at the invasion front of colorectal adenocarcinomas tumour cells, singly or in small aggregates, become detached from the neoplastic glands. This morphological feature is increasingly being recognized as a strong and robust adverse prognostic factor. Biologically, tumour budding is closely related to the epithelial-mesenchymal transition. In this review the morphological features of tumour budding are discussed, as observed by the surgical pathologist reporting colorectal carcinoma resection specimens. The morphological features are put into context with the rapidly expanding knowledge of the epithelial-mesenchymal transition in general, and the molecular pathology of colorectal carcinoma in particular. Finally, a systematic analysis of the relevant published clinicopathological studies emphasizes the potential of tumour budding as a prognostic factor for routine surgical pathology.

Phenotypes of invasion in sporadic colorectal carcinomas related to aberrations of the adenomatous polyposis coli (APC ) gene

AIMS

To determine whether the dissociation of tumour cells from neoplastic glands in colorectal carcinomas is caused by disruption of the wnt-signalling pathway and whether the adenomatous polyposis coli (APC) protein is implicated in this.

METHODS AND RESULTS

In a series of 99 clinically sporadic colorectal carcinomas, APC exon 15 mutations, loss of heterozygosity (LOH) and promoter methylation were found in 49, 20 and 23 cases, respectively. Singly, these APC aberrations were not associated with the degree of tumour cell dissociation, but dissociation was higher for the cases with combined APC mutation and LOH. Immunohistochemical beta-catenin translocation to the nucleus correlated with APC aberrations. Tumour growth pattern (expansive/infiltrative/diffuse) and tumour stroma (desmoplastic common-type versus keloid-like) showed a statistically significant association with tumour cell dissociation and with beta-catenin translocation. Of other molecular alterations tested (p53 mutation; LOH at 17p13, 18q, 9p21; CpG island methylator phenotype), only the highly microsatellite unstable status (n = 11) was negatively associated.

CONCLUSIONS

In colorectal carcinomas, wnt dysregulation relates to APC aberrations, but wnt dysregulation and APC aberrations are not strictly required for tumour cell dissociation, and additional and/or alternative factors must play a role. Of these, outside-in signalling by cancer cell-matrix interactions, as partially mirrored in histomorphological features, could be important.

Cytoplasmic expression of p27kip1 is associated with a favourable prognosis in colorectal cancer patients

AIM: To evaluate the prognostic significance of p27^kip1 in colorectal cancer patients.

METHODS: Cytoplasmic and nuclear p27^kip1 expression was evaluated in 418 colorectal cancers using tissue microarrays. Data were associated with known patient and tumor variables and long-term patient outcomes, providing further insight into the mechanisms by which p27^kip1 may influence tumor development.

RESULTS: Nuclear and cytoplasmic p27^Kip1 expressions were detected in 59% and 19% of tumors respectively. Cytoplasmic p27^Kip1 was almost invariably associated with positive nuclear p27^Kip1 expression. Neither case correlated with known clinical or pathological variables, including tumor stage, grade or extramural vascular invasion. Furthermore, nuclear p27^kip1 expression had no impact on survival. However, we identified a significant correlation between expression of cytoplasmic p27^kip1 and longer disease-specific survival times. On multivariate analysis, TNM stage and extramural vascular invasion were highly significant independent prognostic factors, with positive cytoplasmic p27 expression showing a trend towards improved patient survival (P = 0.059).

CONCLUSION: These findings support the recent evidence that cytoplasmic p27^kip1 has a distinct and important biological role that can influence tumor outcome.

Assessment of epidermal growth factor receptor (EGFR) expression in primary colorectal carcinomas and their related metastases on tissue sections and tissue microarray

Metastatic colorectal carcinomas (CRC) resistant to chemotherapy may benefit from targeting monoclonal therapy cetuximab when they express the epidermal growth factor receptor (EGFR). Because of its clinical implications, we studied EGFR expression by immunohistochemistry on tissue sections of primary CRC (n=32) and their related metastases (n=53). A tissue microarray (TMA) was generated from the same paraffin blocks to determine whether this technique could be used for EGFR screening in CRC. On tissue sections, 84% of the primary CRC and 94% of the metastases were EGFR-positive. When matched, they showed a concordant EGFR-positive status in 78% of the cases. Moreover, staining intensity and extent of EGFR-positive cells in the primary CRC correlated with those observed in the synchronous metastases. On TMA, 65% of the primary CRC, 66% of the metastases, and 43% of the matched primary CRC metastases were EGFR-positive. There was no concordant EGFR status between the primary and the metastatic sites. A strong discrepancy of EGFR status was noted between TMA and tissue sections. In conclusion, EGFR expression measured in tissue sections from primary CRC and their related metastases was found to be similar and frequent, but it was significantly underestimated by the TMA technique.

Budding invasive margin and prognosis in colorectal cancer – no direct association with β-catenin expression

Cancer cell budding at the invasive margin has been associated with poor prognosis in rectal cancer. beta-Catenin is an adhesion protein involved in the nuclear Wnt/beta-catenin pathway, and mesenchymal transition of colorectal cancer cells. Hence, we investigated the relationship between cancer cell budding at the invasive margin, beta-catenin expression, and 5-year-survival in colorectal cancer. Four hundred and sixty six colorectal cancer specimens were analysed for budding margin, and 108 specimens from the same set for beta-catenin by immunohistochemistry. A budding margin was present in 24.0% of the cases and predicted a poor 5-year-survival (15.4%, P < 0.00001). Nuclear beta-catenin expression increased from the central area towards the invasive margin (P < 0.001), but did not predict budding. Budding margin is an independent factor associated with poor prognosis in colorectal cancer, and could be utilised in diagnostic pathology. Nuclear beta-catenin was often found at the invasive margin, but is unlikely to be the sole cause of budding.

p16(INK4a) promoter methylation and 9p21 allelic loss in colorectal carcinomas: relation with immunohistochemical p16(INK4a) expression and with tumor budding

In colorectal carcinomas, p16(INK4a) inactivation is known to occur by allelic loss and by promoter methylation, but mutations are rare. p16(INK4a) is up-regulated in tumor buds, and the consequent shutdown of proliferation may be a prerequisite for tumor budding. Fifty-seven colorectal carcinomas from a consecutive series were investigated. Using DNA from tissue homogenates, p16(INK4a) promoter methylation was seen in 17 of 57 tumors by methylation-specific polymerase chain reaction, and this could be confirmed using DNA from laser-capture microdissected material in 16 of these cases. A total loss of immunohistochemical p16(INK4a) expression was seen in 6 of 17 tumors with promoter methylation. Quantification of immunohistochemical p16(INK4a) expression for the remaining 11 cases revealed statistically lower frequencies of expression as compared with cases without p16(INK4a) promoter methylation. 9p21 allelic loss was observed in 9 cases, but p16(INK4a) expression in these carcinomas was not reduced. Attempted linear regression of p16(INK4a) expression in tumor buds on the degree of tumor budding, as counted on pan-cytokeratin immunostains, did not show a correlation. p16(INK4a) promoter methylation can completely abrogate p16(INK4a) expression in colorectal carcinomas. In many cases, however, it has an appreciable but only modulatory influence on p16(INK4a) expression. Possibly, methylations are heterozygous, and/or mosaic in colorectal carcinomas and/or methylations are not totally stable but can be lost between carcinoma cell replication cycles. Up-regulation of p16(INK4a) does not seem to be a strict requirement for tumor budding, hence, the absence of a correlation.

Tumour regression and mesorectal lymph node changes after intensified neoadjuvant chemoradiation for carcinoma of the rectum

Neoadjuvant radiation or chemoradiation is currently the treatment of choice for patients with locally advanced carcinoma of the rectum. To assess the effects of chemoradiation on tumour regression and on uninvolved mesorectal lymph nodes, a consecutive series of 76 patients receiving neoadjuvant chemoradiation and a stage-adapted control series of 57 patients without pretreatment were studied. Densities of cells positive for CD4 (T-helper cells), CD8 (cytotoxic T-cells), CD83 (mature dendritic cells), and CD57 (natural killer cells) were determined on immunostains. Tumour regression was graded, and presence or absence of extramural tumour was recorded. The densities of CD4+ T-lymphocytes and CD83+ dendritic cells in the paracortex of mesorectal lymph nodes were observed to be significantly reduced, as were the densities of CD57+ cells in the follicles; densities of CD8+ T-lymphocytes did not differ. Strong, moderate and poor tumour regression was observed in 29, 25, and 22 cases, respectively. For 12 patients, absence of extramural vital or regressing tumour was recorded, indicating pretherapeutic overstaging. The results bring to mind that neoadjuvant chemoradiation as a side effect may have a negative impact on anti-tumour immunity. Together with the drawback of overstaging the results argue for a careful selection of patients.