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.

The aberrant methylation of TSP1 suppresses TGF-beta1 activation in colorectal cancer

Colorectal cancer arises from the progressive accumulation of mutations and epigenetic alterations in colon epithelial cells. Such alterations often deregulate signaling pathways that affect the formation of colon cancer, such as the Wnt, RAS-MAPK and TGF-beta pathways. The tumor promoting effects of mutations in genes, such as APC, have been demonstrated in cancer cell lines and in mouse models of intestinal cancer; however, the biological effects of most epigenetic events identified in colorectal cancer remain unknown. Consequently, we assessed whether the aberrant methylation of TSP1, the gene for thrombospondin 1, a regulator of TGF-beta ligand activation, is an epigenetic mechanism for inhibiting the TGF-beta signaling pathway. We found methylated TSP1 occurs in colon cancer cell lines (33%), colon adenomas (14%) and colon adenocarcinomas (21%). In primary colorectal cancers, loss of TSP1 expression correlated with impaired TGF-beta signaling as indicated by decreased Smad2 phosphorylation and nuclear localization. Furthermore, methylation-induced silencing of TSP1 expression reduced the concentration of secreted active TGF-beta1 and attenuated TGF-beta signaling. Reversal of TSP1 methylation resulted in increased TSP1 mediated activation of the latent LAP:TGF-beta complex and subsequent TGF-beta receptor activation. Our results demonstrate that the aberrant methylation of TSP1 has biological consequences and provide evidence that the aberrant methylation of TSP1 is a novel epigenetic mechanism for suppressing TGF-beta signaling in colorectal cancer.

DeltaNp73alpha regulates MDR1 expression by inhibiting p53 function

The p73 protein is a transcription factor and member of the p53 protein family that expresses as a complex variety of isoforms. DeltaNp73alpha is an N-terminally truncated isoform of p73. We found that DeltaNp73 protein is upregulated in human gastric carcinoma suggesting that DeltaNp73 may play an oncogenic role in these tumors. Although it has been shown that DeltaNp73alpha inhibits apoptosis and counteracts the effect of chemotherapeutic drugs, the underlying mechanism by which this p73 isoform contributes to chemotherapeutic drug response remains to be explored. We found that DeltaNp73alpha upregulates MDR1 mRNA and p-glycoprotein (p-gp), which is involved in chemotherapeutic drug transport. This p-gp upregulation was accompanied by increased p-gp functional activity in gastric cancer cells. Our data suggest that upregulation of MDR1 by DeltaNp73alpha is mediated by interaction with p53 at the MDR1 promoter.

Desmethyl derivatives of indomethacin and sulindac as probes for cyclooxygenase-dependent biology

Cyclooxygenases (COX) have been implicated in the etiology of a number of diseases, but defining the precise contribution of COXs to these diseases is challenging. Potent COX inhibitors exist, but they display off-target effects. 2'-Desmethyl derivatives of indomethacin and sulindac sulfide were synthesized that demonstrated reduced COX inhibitory activity but were inducers of peroxisome proliferator-activated receptor gamma-dependent transcription, adipocyte differentiation, or apoptosis of colon cancer cell lines. 2'-Desmethylindomethacin demonstrated gastrointestinal toxicity lower than that of indomethacin in C57BL6 mice, highlighting the importance of COX activity in maintaining gastrointestinal homeostasis and establishing that COX inhibition contributes to gastrointestinal toxicity by nonsteroidal antiinflammatory drugs. These compounds serve as useful probes of COX-dependent biology and may represent leads for antidiabetic and anticancer drugs.

Evidence for the role of aberrant DNA methylation in the pathogenesis of Lynch syndrome adenomas

Colorectal cancer (CRC) forms through a series of histologic steps that are accompanied by mutations and epigenetic alterations, which is called the polyp-cancer sequence. The role of epigenetic alterations, such as aberrant DNA methylation, in the polyp-cancer sequence in sporadic CRC and particularly in hereditary colon cancer is not well understood. Consequently, we assessed the methylation status of CDKN2A/p16, MGMT, MLH1 and p14(ARF) in adenomas arising in the Lynch syndrome, a familial colon cancer syndrome caused by MLH1 and MSH2 mutations, to determine if DNA methylation is a "second hit" mechanism in CRC and to characterize the role of DNA methylation in the polyp phase of the Lynch syndrome. We found MLH1 and p14(ARF) are methylated in 53 and 60% of the Lynch syndrome adenomas and in 4 and 20% of sporadic adenomas, whereas CDKN2A/p16 and MGMT are methylated in 6 and 14% of the Lynch syndrome adenomas versus 50 and 64% of sporadic adenomas. Therefore, the frequency and pattern of gene methylation varies between the Lynch syndrome and sporadic colon adenomas, implying differences in the molecular pathogenesis of the tumors. MLH1 methylation in the Lynch syndrome adenomas suggests gene methylation might have a role in the initiation of these neoplasms.

Ménétrier disease and gastrointestinal stromal tumors: hyperproliferative disorders of the stomach

Ménétrier disease and gastrointestinal stromal tumors (GISTs) are hyperproliferative disorders of the stomach caused by dysregulated receptor tyrosine kinases (RTKs). In Ménétrier disease, overexpression of TGF-alpha, a ligand for the RTK EGFR, results in selective expansion of surface mucous cells in the body and fundus of the stomach. In GISTs, somatic mutations of the genes encoding the RTK KIT (or PDGFRA in a minority of cases) result in constitutive kinase activity and neoplastic transformation of gut pacemaker cells (interstitial cells of Cajal). On the basis of the involvement of these RTKs in the pathogenesis of these disorders, Ménétrier disease patients have been effectively treated with a blocking monoclonal antibody specific for EGFR and GIST patients with KIT and PDGFRA tyrosine kinase inhibitors.

CpG island methylation of genes accumulates during the adenoma progression step of the multistep pathogenesis of colorectal cancer

Genetic alterations occur during the adenoma-carcinoma sequence of colon cancer formation and drive the initiation and progression of colon cancer formation. The aberrant methylation of genes is an alternate, epigenetic mechanism for silencing tumor suppressor genes in colon cancer. The aim of this study was to determine on a global and gene-specific level the role of CpG island methylation in the initiation and progression of colon cancer. Consequently, we assessed the frequency of gene methylation in tumors representative of the commonly recognized histological steps of the adenoma-carcinoma progression sequence through the analysis of eight genes previously identified to be methylated in colon cancer, MGMT, HLTF, MLH1, p14(ARF), CDKN2A, TIMP3, THBS1, and CDH1. We observed that the proportion of tumors carrying methylated alleles increased from adenomas to adenocarcinomas but that the proportion of tumors with methylated alleles was not different between adenocarcinomas and metastases (69% versus 90%, P = 0.01 and 90% versus 81%, P > 0.05). The most substantial difference occurred between early and advanced adenomas (47% versus 84%, P = 0.018). Furthermore, we observed that the frequency of gene methylation at the different steps of the progression sequence varied between genes. Thus, the aberrant methylation of genes appears to increase most significantly during the progression of early adenomas to advanced adenomas, and the frequency of specific gene methylation at the different steps of the adenoma-carcinoma progression sequence varies in a gene-specific fashion.

Expression of Pdx-1 in human gastric metaplasia and gastric adenocarcinoma

Metaplastic lineages represent critical putative preneoplastic precursors for gastrointestinal metaplasia. Two metaplastic processes are associated with gastric cancer: intestinal metaplasia (the presence of intestinal goblet cell containing lineages in the stomach) and spasmolytic polypeptide-expressing metaplasia (SPEM; antralization of the gastric fundus). The transcription factor Pdx-1 is expressed in the adult pancreatic islet cells as well as the gastric antrum and duodenum. We have previously noted the increase in Pdx-1 expression in models of TGFalpha overexpression in mice but not in other models of SPEM in rodents. We have therefore sought to examine the presence of Pdx-1 expression in gastric metaplasias and gastric adenocarcinoma in humans. Tissue microarrays containing gastric cancers from the fundus and antrum and samples of SPEM and intestinal metaplasia were immunostained for Pdx-1. Nuclear Pdx-1 expression was observed in only 50% of antral-derived cancers and was present in 40% of fundic tumors. Pdx-1 expression did not correlate with clinical outcome. Although SPEM lineages did not show any staining for Pdx-1, intestinal metaplasia showed strong nuclear staining for Pdx-1. Thus, Pdx-1 expression is not associated with antralizing metaplasia (SPEM) but is associated with intestinal metaplasia. Given the pattern of normal Pdx-1 expression in the duodenum, goblet cell metaplasia in the stomach may reflect the adoption of a duodenal lineage paradigm.

Randomized phase II trial of the clinical and biological effects of two dose levels of gefitinib in patients with recurrent colorectal adenocarcinoma

PURPOSE

The clinical objective of this trial was to evaluate gefitinib in patients with metastatic colorectal cancer that had progressed despite prior treatment. Serial tumor biopsies were performed when possible and analyzed for activation of the epidermal growth factor receptor (EGFR) signaling pathway. Serial serum samples were measured for amphiregulin and transforming growth factor-alpha (TGFalpha).

PATIENTS AND METHODS

One hundred fifteen patients were randomly assigned to receive gefitinib 250 or 500 mg orally once a day. One hundred ten patients were assessable for clinical efficacy. Biologic evaluation was performed on paired tumor samples from 28 patients and correlated with clinical outcome.

RESULTS

Median progression-free survival was 1.9 months (95% CI, 1.8 to 2.1 months) and 4-month progression-free survival rate was 13% +/- 5%. One patient achieved a radiographic partial response (RR = 1%; 95% CI, 0.01% to 5%). Median survival was 6.3 months (95% CI, 5.1 to 8.2 months). The most common adverse events were skin rash, diarrhea, and fatigue. In the biopsy cohort, expression of total or activated EGFR, activated Akt, activated MAP-kinase, or Ki67 did not decrease following 1 week of gefitinib. However, a trend toward decreased post-treatment levels of activated Akt and Ki67 was observed in patients with a PFS higher than the median, although these did not reach the .05 level of significance.

CONCLUSION

Gefitinib is inactive as a single agent in patients with previously treated colorectal cancer. In tumor samples, gefitinib did not inhibit activation of its proximal target, EGFR. Trends were observed for inhibition of downstream regulators of cellular survival and proliferation in patients achieving longer progression-free survival.

A Double-blind Placebo-Controlled Study of Emtricitabine in Chronic Hepatitis B

BACKGROUND

Emtricitabine is a nucleoside analogue approved for treatment of human immunodeficiency virus 1 with clinical activity against hepatitis B virus (HBV).

METHODS

To compare the safety and efficacy of emtricitabine with placebo in patients with HBV, we conducted a randomized (2:1), double-blind study at 34 sites in North America, Asia, and Europe that enrolled adults between November 2000 and July 2002 who had chronic HBV infection but had never been exposed to nucleoside or nucleotide treatment. Each patient received either 200 mg of emtricitabine (n=167) or placebo (n=81) once daily for 48 weeks and underwent a pretreatment and end-of-treatment liver biopsy. Histologic improvement was defined as a 2-point reduction in Knodell necroinflammatory score with no worsening in fibrosis.

RESULTS

At the end of treatment, 103 (62%) of 167 patients receiving active treatment had improved liver histologic findings vs 20 (25%) of 81 receiving placebo (P<.001), with significance demonstrated in subgroups positive (P<.001) and negative (P=.002) for hepatitis Be (HBe) antigen. Serum HBV DNA readings showed less than 400 copies/mL in 91 (54%) of 167 patients in the emtricitabine group vs 2 (2%) of 81 in the placebo group (P<.001); alanine aminotransferase levels were normal in 65% (109/167) vs 25% (20/81), respectively (P<.001). At week 48, 20 (13%) of 159 patients in the emtricitabine group with HBV DNA measured at the end of treatment had detectable virus with resistance mutations (95% confidence interval, 8%-18%). The rate of seroconversion to anti-HBe (12%) and HBe antigen loss were not different between arms. The safety profile of emtricitabine during treatment was similar to that of placebo. Posttreatment exacerbation of HBV infection developed in 23% of emtricitabine-treated patients.

CONCLUSION

In patients with chronic HBV, both positive and negative for HBe antigen, 48 weeks of emtricitabine treatment resulted in significant histologic, virologic, and biochemical improvement.

Rab11a immunohistochemical analysis does not distinguish indefinite, low-, and high-grade dysplasia in Barrett esophagus

Our aim was to determine whether p53 and Rab11a immunoreactivity enhance diagnostic assessment of esophageal dysplasia. Histologic sections from 68 cases of Barrett esophagus obtained as part of a 12-institution study were stained with antibodies to p53 and Rab11a, randomized, and coded. The mucosal surface layer and deeper glands were scored blindly on a semiquantitative scale. The correlations between p53 and Rab11a scoring with the consensus diagnosis of dysplasia were analyzed. The histologic scale was as follows: no dysplasia, indefinite, low-grade dysplasia, high-grade dysplasia, intramucosal carcinoma, and invasive carcinoma. Rab11a staining was most prominent in epithelia negative for dysplasia but with regenerative features. There was an inverse relationship between Rab11a staining and findings of surface dysplasia (P < .02, chi(2)). However, statistical significance largely reflected loss of Rab11a immunoreactivity in intramucosal and invasive carcinoma, which was not a diagnostic dilemma. There was a strong positive correlation of p53 immunoreactivity with an increasing degree of epithelial dysplasia and carcinoma (P < .03, chi(2)). Rab11a immunoreactivity did not enhance the diagnostic assessment of dysplasia in Barrett esophagus. The previously reported positive correlation of p53 immunoreactivity with the presence of dysplasia in Barrett esophagus was confirmed.

Polyclonality of familial murine adenomas: analyses of mouse chimeras with low tumor multiplicity suggest short-range interactions

In previous studies demonstrating the polyclonal structure of familial intestinal adenomas, high tumor multiplicity made it difficult to eliminate the possibility that polyclonality arose by the random collision of distinct initiated clones as opposed to some form of clonal interaction. We sought to test further the random collision hypothesis. Chimeric mice carrying the multiple intestinal neoplasia (Min) mutation of the adenomatous polyposis coli gene (Apc) and homozygous for the tumor resistance allele of the Mom1 locus were established. These chimeras also display a strong propensity for tumors of polyclonal structure, despite their markedly reduced tumor multiplicity. Considering tumor sizes and multiplicities, the observed fraction of overtly polyclonal heterotypic adenomas was significantly higher than predicted by the random collision hypothesis. This finding supports models of polyclonality involving interaction among multiple initiated clones. The extent of clonal interaction was assessed by statistical analyses that relate the observed frequency of overtly polyclonal heterotypic tumors to the geometry of the chimeric patches and the pattern of underlying crypts. These statistical calculations indicate that the familial adenomas of the Apc(Min/+) mouse may commonly form through interactions between clones as close as 1-2 crypt diameters apart.

Gene expression profile analysis of mouse colon embryonic development

During late embryogenesis, the mouse colon develops from a pseudostratified, undifferentiated endoderm to a single-layered columnar epithelium with accompanying mesenchymal maturation. To identify regulatory genetic programs underlying these morphological changes, we profiled gene expression of the developing mouse colon by microarray from embryonic day (E)13.5 to E18.5. Unbiased cluster analysis of 13,484 cDNA elements revealed two distinct groups of genes whose expression changes reflect the dynamic morphological events of the epithelium and mesenchyme during this period. Additional analyses revealed two subsets of genes whose expression is either upregulated or downregulated over the same developmental period. Of those genes whose expression increases from E13.5 to E18.5 (n = 158), known functions include acquisition and/or maintenance of colonic differentiation. Genes whose transcription is downregulated over this period (n = 49) have demonstrated roles in nuclear organization, transcriptional regulation, and cell proliferation. These results provide the basis for a molecular portrait of colonic development during late embryogenesis and should be a valuable resource for investigators interested in colonic development and neoplasia, as well as comparative organogenesis.

Establishing a tumour bank: banking, informatics and ethics

The six divisions of the Cooperative Human Tissue Network in the USA bank and distribute tens of thousands of tissue specimens to researchers annually. Major operational concerns include: maintaining tissue integrity, managing informatics, and protecting patient confidentiality. Increasing molecular genetics testing is also resulting in an increased demand for high-quality nucleic acids.

Over-expression of cyclin D1 regulates Cdk4 protein synthesis

Increased Cdk4 expression occurs coincident with over-expression of cyclin D1 in many human tumours and tumourigenic mouse models. Here, we investigate both in vivo and in vitro the mechanism by which Cdk4 expression is regulated in the context of cyclin D1 over-expression. Cdk4 mRNA levels in cyclin D1-over-expressing tissue and cultured cells were unchanged compared with controls. In contrast, Cdk4 protein levels were increased in cyclin D1-over-expressing tissue and cells versus their respective controls. This increase was not due to altered protein stability, but appeared to be due to an increase in Cdk4 protein synthesis. We also performed immunoprecipitation and in vitro kinase assays to demonstrate an increase in cyclin D1-Cdk4 complex formation and associated kinase activity. Blocking cyclin D1 expression resulted in diminished Cdk4 protein but not mRNA levels. These findings suggest a mechanism by which Cdk4 expression is increased in the context of cyclin D1 over-expression during tumourigenesis.

The role of [18F]fluorodeoxyglucose positron emission tomography imaging in the evaluation of hepatocellular carcinoma

It has been well established that hepatocellular carcinomas (HCCs) accumulate [18F]fluorodeoxyglucose (FDG) to varying degrees; this is thought to be due to differing amounts of FDG-6-phosphatase activity. The purpose of this study was to evaluate the impact of FDG imaging on the management of patients diagnosed with hepatocellular carcinoma. We conducted a retrospective review of the clinical data of 91 consecutive patients diagnosed with HCC who underwent FDG-positron emission tomography (PET) imaging between August 1993 and March 2001. The patients were divided into two groups. In Group one 67 of 91 (74%) patients were evaluated for proven but untreated hepatic lesions using PET. In Group two the remaining 24 patients (26%) were referred for evaluation of HCC recurrence but did not have prior PET. The FDG images were acquired with two dedicated PET tomographs [Siemens ECAT 933, CTI (Knoxville, TN) and GE Advance, General Electric Medical Systems (Milwaukee, WI)] one hour after the intravenous administration of 10 mCi of FDG. Tumor biopsy or resection specimens were available for review from 34 patients and were evaluated for histologic grade, presence of cirrhosis, tumor necrosis, and intratumoral fibrosis. In group one 43 of 67 (64%) of the HCCs accumulated FDG. Sixteen of the 43 patients in whom FDG was accumulated had multiple subsequent FDG-PET scans either for monitoring therapy or for detection of recurrence. FDG-PET imaging had an impact on the management of 20 of these patients: by guiding the biopsy at the metabolically active site of a large necrotic tumor (one), by identifying distant metastases (five), by monitoring the response to treatment with hepatic chemoembolization and guiding additional regional therapy (12), and by detecting recurrence (two). In group two recurrence and/or metastases were demonstrated with FDG-PET imaging in six of 24 (25%) patients, three of whom had multiple subsequent FDG-PET scans to monitor their treatment. Higher histopathologic grade and intratumoral fibrosis but not necrosis or cirrhosis correlated with PET positivity. In this study only 64 per cent of HCCs accumulated FDG. Despite this limitation FDG-PET imaging remains a useful tool in the diagnosis and treatment of HCC. FDG-PET imaging had a clinically significant impact in 26 of 91 (28%) patients with HCC. This includes detection of unsuspected metastatic disease in high-risk patients-including liver transplant candidates-and monitoring response to hepatic-directed therapy. FDG-PET should be considered as part of the workup and management of selected patients with HCC.

The Role of [18F]Fluorodeoxyglucose Positron Emission Tomography Imaging in the Evaluation of Hepatocellular Carcinoma

It has been well established that hepatocellular carcinomas (HCCs) accumulate [18F]fluorodeoxy-glucose (FDG) to varying degrees; this is thought to be due to differing amounts of FDG-6-phosphatase activity. The purpose of this study was to evaluate the impact of FDG imaging on the management of patients diagnosed with hepatocellular carcinoma. We conducted a retrospective review of the clinical data of 91 consecutive patients diagnosed with HCC who underwent FDG-positron emission tomography (PET) imaging between August 1993 and March 2001. The patients were divided into two groups. In Group one 67 of 91 (74%) patients were evaluated for proven but untreated hepatic lesions using PET. In Group two the remaining 24 patients (26%) were referred for evaluation of HCC recurrence but did not have prior PET. The FDG images were acquired with two dedicated PET tomographs [Siemens ECAT 933, CTI (Knoxville, TN) and GE Advance, General Electric Medical Systems (Milwaukee, WI)] one hour after the intravenous administration of 10 mCi of FDG. Tumor biopsy or resection specimens were available for review from 34 patients and were evaluated for histologic grade, presence of cirrhosis, tumor necrosis, and intratumoral fibrosis. In group one 43 of 67 (64%) of the HCCs accumulated FDG. Sixteen of the 43 patients in whom FDG was accumulated had multiple subsequent FDG-PET scans either for monitoring therapy or for detection of recurrence. FDG-PET imaging had an impact on the management of 20 of these patients: by guiding the biopsy at the metabolically active site of a large necrotic tumor (one), by identifying distant metastases (five), by monitoring the response to treatment with hepatic chemoembolization and guiding additional regional therapy (12), and by detecting recurrence (two). In group two recurrence and/or metastases were demonstrated with FDG-PET imaging in six of 24 (25%) patients, three of whom had multiple subsequent FDG-PET scans to monitor their treatment. Higher histopathologic grade and intratumoral fibrosis but not necrosis or cirrhosis correlated with PET positivity. In this study only 64 per cent of HCCs accumulated FDG. Despite this limitation FDG-PET imaging remains a useful tool in the diagnosis and treatment of HCC. FDG-PET imaging had a clinically significant impact in 26 of 91 (28%) patients with HCC. This includes detection of unsuspected metastatic disease in high-risk patients—including liver transplant candidates—and monitoring response to hepatic-directed therapy. FDG-PET should be considered as part of the workup and management of selected patients with HCC.

Macrophages are necessary for maximal nuclear factor-kappa B activation in response to endotoxin

To define the role of macrophages in regulating the lung's response to Escherichia coli endotoxin (lipopolysaccharide [LPS]), depletion of macrophages was accomplished by administration of dichloromethylene diphosphonate (clodronate) delivered via intratracheal (i.t.) and/or intravenous (i.v.) routes. Clodronate reduced the number of macrophages in lung lavage 48 h after either i.t. or i.v. administration, but combined i.t. + i.v. clodronate achieved the most profound depletion (90%). Although i.t. clodronate alone had little effect on the evolution of lung inflammation, combined i.t. + i.v. clodronate treatment decreased neutrophilic alveolitis 4 h after exposure to aerosolized LPS by 80% compared with mice treated with empty liposomes. This decrease was associated with impaired activation of nuclear factor (NF)-kappa B and lower concentrations of tumor necrosis factor (TNF)-alpha in lung lavage fluid. Combined i.t. + i.v. clodronate markedly reduced lung NF-kappa B activation and the intensity of neutrophilic alveolitis after intraperitoneal (i.p.) LPS; however, i.v. clodronate alone had no effect on NF-kappa B activation in either liver or lung tissue or the development of neutrophilic alveolitis. We conclude that generalized macrophage depletion reduces NF-kappa B activation, generation of cytokines, and neutrophilic lung inflammation in response to gram negative bacterial endotoxin. These findings define the role of the macrophage as a critical component for initiation of the NF-kappa B-dependent innate immune response.

Radical resection improves survival for patients with pT2 gallbladder carcinoma

Radical resection (wedge resection of the gallbladder bed and dissection of the hepatoduodenal ligament, portal, and celiac lymph nodes) has been reported to improve survival from pathologic T2 gallbladder carcinoma (pT2 GBCa; invasion through the muscularis without perforation of the serosa). We report our experience and the outcome of patients with pT2 GBCa. Between 1989 and 2000 at Vanderbilt University Medical Center ten patients were found to have pT2 disease after cholecystectomy. The patients had an average age of 64+/-13 years and underwent either radical resection (n = 5) or no further surgical therapy (n = 5). Of the patients who underwent cholecystectomy only, one (20%) is still alive at 27 months and four (80%) died of recurrent GBCa between 6.5 and 21 months. For the patients who underwent radical resection all five are alive at 15 to 83 months with no recurrence. The proportion of patients surviving pT2 GBCa after radical resection was significantly greater than with cholecystectomy alone (P < 0.05). The difference in length of survival between the two groups was also significant (P < 0.05). Morbidity after radical resection was low (pancreatic leak in one patient), and there were no operative mortalities. Radical resection significantly improved survival over cholecystectomy alone for patients with pT2 GBCa. The procedure has low morbidity and mortality rates. Therefore a radical resection operation is indicated for patients with pT2 GBCa.

A cyclooxygenase-2 inhibitor (SC-58125) blocks growth of established human colon cancer xenografts

Selective COX-2 inhibitors reduce adenoma formation and cancer progression in rodent models of colorectal cancer. To assess the therapeutic activity of selective COX-2 inhibitors, we tested the effect of SC-58125 treatment on the growth of human colon carcinoma cells in nude mice. Delaying treatment by 2, 4, or 7 weeks following implantation of the carcinoma cells resulted in a significant inhibition of tumor growth. Furthermore, short-term (48 hours) treatment with SC-58125 was sufficient to attenuate tumor growth for up to 15 days. SC-58125 treatment did not alter the rate at which cells underwent apoptosis, but did result in a delayed progression through the cell cycle at the G(2)/M transition. Accordingly, p34(cdc2) protein levels and activity were decreased following SC-58125 treatment. We conclude that SC-58125 primarily exerts a cytostatic effect in vivo, which is likely to be mediated through inhibition of progression through the G(2)/M phase of the cell cycle.