Morphologic and Immunohistochemical Analysis of Mesenteric and Retroperitoneal Mucinous Cystic Neoplasms

Introduction/Objective

Mucinous cystic neoplasms (MCN) are neoplasms with mucinous epithelium surrounded by ovarian-type stroma, occurring in the pancreas and liver. Reports of MCN arising outside the liver and pancreas are rare. We aim to perform a clinicopathologic, morphologic and immunohistochemical analysis of mesenteric and retroperitoneal MCN arising separate from the pancreas and liver.

Methods

Seven mesenteric or retroperitoneal MCN (n=7) were identified and clinical and radiologic information obtained, where available. The following immunostains were performed on each case: keratin 7, keratin 19, estrogen receptor, progesterone receptor, calretinin, inhibin-α, and SF-1.

Results

All seven MCN were from women with a median age of 41 years (range: 28-70 years). The median size of the MCN was 8cm (range: 8-14.5 cm) involving the retroperitoneum (n=5) and mesoappendix (n=2). One patient was diagnosed with a synchronous right ovarian mucinous cystadenoma. Morphologically, all MCN displayed mucinous or mixed non-mucinous-mucinous cuboidal to columnar epithelium without dysplasia. Ovarian-type stroma was identified underlying the epithelium with foci of luteinized stromal cells. The ovarian-type stroma expressed estrogen and progesterone receptors in all seven cases, two cases stained with SF-1 showed diffuse strong stromal positivity, and one case stained with inhibin showed focal strong stromal positivity. Additional immunohistochemical analysis with CK7, CK19, calretinin, inhibin-α, and SF-1 on all cases is pending.

Conclusion

Clinicopathologic, morphologic, and immunohistochemical characteristics of mesenteric/retroperitoneal MCN are similar to their pancreas and liver counterparts. Familiarity with this entity and knowing it can arise in mesenteric/retroperitoneal locations is important for accurate diagnosis and to distinguish it from mucinous carcinoma, teratoma, endometriosis and other differential diagnoses which have different implications. We propose that mesenteric/retroperitoneal MCN may possibly arise from primordial germ cells that underwent aberrant migration during their retroperitoneal descent through the fetal dorsal mesentery which gives rise to the neck and body of the pancreas as well as the mesentery and mesoappendix.

Prediction of overall survival in stage II and III colon cancer beyond TNM system: a retrospective, pooled biomarker study

Background

TNM staging alone does not accurately predict outcome in colon cancer (CC) patients who may be eligible for adjuvant chemotherapy. It is unknown to what extent the molecular markers microsatellite instability (MSI) and mutations in BRAF or KRAS improve prognostic estimation in multivariable models that include detailed clinicopathological annotation.

Patients and methods

After imputation of missing at random data, a subset of patients accrued in phase 3 trials with adjuvant chemotherapy (n = 3016)-N0147 (NCT00079274) and PETACC3 (NCT00026273)-was aggregated to construct multivariable Cox models for 5-year overall survival that were subsequently validated internally in the remaining clinical trial samples (n = 1499), and also externally in different population cohorts of chemotherapy-treated (n = 949) or -untreated (n = 1080) CC patients, and an additional series without treatment annotation (n = 782).

Results

TNM staging, MSI and BRAFV600E mutation status remained independent prognostic factors in multivariable models across clinical trials cohorts and observational studies. Concordance indices increased from 0.61-0.68 in the TNM alone model to 0.63-0.71 in models with added molecular markers, 0.65-0.73 with clinicopathological features and 0.66-0.74 with all covariates. In validation cohorts with complete annotation, the integrated time-dependent AUC rose from 0.64 for the TNM alone model to 0.67 for models that included clinicopathological features, with or without molecular markers. In patient cohorts that received adjuvant chemotherapy, the relative proportion of variance explained (R2) by TNM, clinicopathological features and molecular markers was on an average 65%, 25% and 10%, respectively.

Conclusions

Incorporation of MSI, BRAFV600E and KRAS mutation status to overall survival models with TNM staging improves the ability to precisely prognosticate in stage II and III CC patients, but only modestly increases prediction accuracy in multivariable models that include clinicopathological features, particularly in chemotherapy-treated patients.

Characterisation of familial colorectal cancer Type X, Lynch syndrome, and non-familial colorectal cancer

BACKGROUND

Familial Colorectal Cancer Type X (FCCTX) is defined as individuals with colorectal cancer (CRC) who families meet Amsterdam Criteria-1 (AC1), but whose tumours are DNA-mismatch-repair-proficient, unlike Lynch syndrome (LS). FCCTX does not have an increased risk of extra-colonic cancers. This analysis compares epidemiologic and clinicopathologic features among FCCTX, LS, and 'non-familial' (non-AC1) CRC cases.

METHODS

From the Colon Cancer Family Registry, FCCTX (n=173), LS (n=303), and non-AC1 (n=9603) CRC cases were identified. Questionnaire-based epidemiologic information and CRC pathologic features were compared across case groups using polytomous logistic regression.

RESULTS

Compared with LS, FCCTX cases were less likely to be current (vs never) smokers; have a proximal subsite (vs rectal) tumour; or have mucinous histology, poor differentiation, or tumour-infiltrating lymphocytes. There were no observed differences in co-morbidities or medication usage.

CONCLUSIONS

FCCTX were less likely to be current tobacco users; other exposures were similar between these groups. Histopathologic differences highly suggestive of LS CRCs do not appear to be shared by FCCTX.

Estrogen receptors evolution in neoadjuvant aromatase inhibitor (AI) therapy for breast cancer in elderly women: stability of hormonal receptor expression during treatment

In France, 20% of breast cancers occur in women over the age of 70 and 10% in women over the age of 80. As these women are not included in screening programs, breast cancer is often diagnosed later, at the stage of a large tumor.

PURPOSE

To analyze clinical response, possibilities of conservative treatment and course of hormonal receptors in patients receiving neoadjuvant aromatase inhibitor (AI) therapy for at least 6 months.

PATIENTS AND METHODS

There were 75 patients, with a mean age of 75 +/- 8 years (range, 58-91 years) received AI for 6 months after the diagnosis of invasive breast cancer with positive hormonal receptors. Clinical and radiologic tumor reduction, the number of conservative treatments and the course of estrogens receptor-labeled cells were determined for each patient.

RESULTS

All but 1 of these patients obtained clinical reduction of their tumor. Of these, 86% patients received conservative treatment. In the majority of patients, estrogen receptor (ER) level did not vary between the initial assay and analysis of the operative specimen.

DISCUSSION AND CONCLUSION

Aromatase inhibitors are effective as neoadjuvant therapy in ER positive elderly patients with large tumors, as is tamoxifen. Changes in hormone receptor expression during treatment do not predict clinical response. In our experience, neoadjuvant AI therapy should be administered for at least 6 months to optimize clinical response before deciding upon surgery. Discrepancy observed in the literature could be explained by the duration of the treatment.

MYC activation associated with the integration of HPV DNA at the MYC locus in genital tumors

To determine whether integration of human papillomavirus (HPV) DNA sequences could lead to the deregulation of genes implied in oncogenesis, we analysed the HPV integration sites in a series of nine cell lines derived from invasive genital carcinomas. Using in situ hybridization, HPV16 or 18 sequences were found at chromosome band 8q24, the localization of MYC, in IC1, IC2, IC3, IC6 and CAC-1 cells and at other sites in IC4, IC5, IC7 and IC8 cells. We then localized viral sequences at the molecular level and searched for alterations of MYC structure and expression in these cells. MYC genomic status and viral integration sites were also analysed in primary tumors from which IC1, IC2, IC3 and IC6 cells were derived. In IC1, IC2 and CAC-1 cells, HPV DNA was located within 58 kb of MYC, downstream, upstream, or within MYC. In IC3 and IC6 cells, HPV DNA was located 400-500 kb upstream of MYC. Amplification studies showed that, in IC1, IC2 and IC3, viral and MYC sequences were co-amplified in an amplicon between less than 50 and 800 kb in size. MYC amplification was also observed in primary tumors, indicating that this genetic alteration, together with viral insertion at the MYC locus, had already taken place in vivo. MYC was not amplified in the other cell lines. MYC mRNA and protein overexpression was observed in the five cell lines in which the HPV DNA was inserted close to the MYC locus, but in none of the lines where the insertion had occurred at other sites. MYC activation, triggered by the insertion of HPV DNA sequences, can be an important genetic event in cervical oncogenesis.

Analysis of correlation between mitotic index, MIB1 score and S-phase fraction as proliferation markers in invasive breast carcinoma. Methodological aspects and prognostic value in a series of 257 cases

BACKGROUND

The study was designed in order to evaluate the degree of correlation of mitotic index (MI), Ki67 (MIB1) score and S-phase fraction (SPF) as markers of cell proliferation and prognosis in breast cancer.

MATERIALS AND METHODS

The series analysed corresponded to 257 consecutive invasive breast carcinoma, treated at the Institut Curie, France, in 1995. Nottingham histological grade and MIB1 semiquantitative and quantitative score were assessed on histological sections, whereas SPF was calculated using flow cytometry analysis of fine-needle aspiration products. Proliferation indices were compared to pathological data and to overall survival (OS) and disease-free survival (DFS) (minimum follow-up: 72 months).

RESULTS

The median values for the proliferation markers were 9/10 HPF for MI, 32.4% for MIB1 and 3.7% for SPF. A high rate of correlation (r=0.96; p<0.001) was observed between semi-quantitative and quantitative MIBI evaluation. A positive correlation was found between the three markers (r ranging from 0.54 to 0.61;p<0.001). Univariate analysis of markers associated to disease outcome showed that MIB1, axillary node status (N) and progesterone receptor (PR) status were significantly associated with OS and that MIB1 and SPF were associated with DFS, together with node and hormone receptor status. In multivariate analysis, when proliferation markers were adjusted on the N and PR status, only MIB1 retained a prognostic value for OS (RR= 1.83) [1.00;3.35] and SPF for DFS (RR= 1.58) [1.02-2.44] (p=0.04).

CONCLUSION

A good level of correlation was observed between the values of the three markers of tumour cell proliferation analysed. In this series of invasive breast cancers, MIB1 immunostaining was found to be a prognostic marker of both OS and DFS. The median (32.4%) was a valuable cut-off value for prognostic assessment. Semi-quantitative and quantitative evaluations provided very similar values. MIB1 can thus be considered as a reliable prognostic maker, usable in small size tissue specimens which are inappropriate for MI or SPF analysis. The impact of MIB1 compared to that of the other proliferative markers will be further assessed in a subgroup of T1N0M0 for which the prognostic assessment is of major interest.

Increased cell size and Akt activation in HER-2/neu-overexpressing invasive ductal carcinoma of the breast

AIMS

To determine whether cell size is related to HER-2/neu status and/or to Akt activation in breast carcinomas. HER-2/neu overexpression is observed in 20-30% of invasive breast carcinomas with poor pronostic features, but little is known about the cell phenotype associated with HER-2/neu activation. Akt has been found to be involved in the HER-2/neu signal transduction pathway and Akt activation has been associated with increased cell size in various models.

METHODS AND RESULTS

A case-control study of invasive ductal carcinoma of the breast was carried out, including 21 cases displaying HER-2/neu overexpression and 20 HER-2/neu negative controls. Cytoplasmic and nuclear sizes were measured on digitized histological pictures using cell image analysis software. Akt expression analysis was performed by immunohistochemistry on formalin-fixed histological sections using an anti-phosphorylated-Akt (Ser473) antibody.

RESULTS

HER-2/neu-overexpressing carcinomas had a mean nuclear size of 75 +/- 22.2 micro m(2) and a mean cytoplasmic size of 187 +/- 52.3 micro m(2). Both values were higher than the nuclear and cytoplasmic size of HER-2/neu-negative cases (nucleus = 58 +/- 24.5 micro m(2), cytoplasm = 133 +/- 56.6 micro m(2); P = 0.02 and P =0.003, respectively). Up to 75% of the tumours with a cell size over 140 micro m(2) were HER-2/neu-positive. Immunohistochemical Akt expression was observed in 19/40 (47.5%) cases. The immunoreactivity was localized in the cytoplasm in eight cases, on the cell membrane in four cases and at both sites in seven cases. One case was not interpretable. Comparison between HER-2/neu and Akt status showed that Akt was detectable at the cell membrane in 43% (9/21) of HER-2/neu-positive and in 10% (2/19) of HER-2/neu-negative cases (P = 0.02).

CONCLUSIONS

HER-2/neu overexpression was consistently associated with increased cell size in invasive ductal carcinoma of the breast. This increase may be related to concomitant Akt activation. The assessment of activated pathways in HER-2/neu-overexpressing breast carcinomas may provide useful information for optimized individual HER-2/neu-targeted therapy.

Wide metastatic spreading in infiltrating lobular carcinoma of the breast

The aim of this study was to determine whether the metastatic potential of breast cancer could be related to phenotypic characteristics of the tumour. Therefore, we compared the metastatic patterns of invasive lobular (ILC) and ductal (IDC) carcinomas. In ILC, we also analysed this pattern according to the histological subtype of the primary and the E-cadherin (EC) expression level. Metastatic ILC cases (n=96) were retrospectively analysed and classified into classical, alveolar, solid, tubulo-lobular, signet ring cells or pleomorphic subtypes. Anatomical distribution of metastases was detailed for every patient and compared with that registered for IDC (n=2749). Immunostaining of EC (HECD1 antibody) was performed in 82 cases. Histologically, 78 of the 96 cases (81%) corresponded to classical ILC. The pleomorphic subtype was observed in 14 cases (15%), a rate that was higher than that expected. Others corresponded to alveolar (2 cases), signet ring cell (1 case) and solid (1 case) subtypes. EC was undetectable in 72/82 cases (88%). The rate of multiple metastases was higher in ILC (25.0%) than in IDC (15.8%) (P=0.016). Metastases were found more frequently in ILC than in IDC in the bone (P=0.02) and/or in various other sites (peritoneum, ovary, digestive tract, skin em leader ) (P<0.001). In ILC, no significant link was found between the localisation(s) of metastases, the histological subtype and the EC status in the primary. In conclusion, in breast carcinomas, the frequency of multiple metastasis was found to be higher in ILC than IDC. This fact may be related to the phenotypic trait of discohesive small cells which characterises ILC. EC loss, observed in most cases of ILC, may result in alterations in cell-cell adhesion and a preferential growth at metastatic sites. A high rate of pleomorphic tumours was observed in the group of metastatic ILC, but the pattern of metastatic site(s) was not related to the histological subtype of the primary.

The reliability of immunohistochemistry as a prescreening method for the diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC)--results of an international collaborative study

Hereditary nonpolyposis colorectal cancer syndrome (HNPCC) is an autosomal dominant condition accounting for 2-5% of all colorectal carcinomas as well as a small subset of endometrial, upper urinary tract and other gastrointestinal cancers. An assay to detect the underlying defect in HNPCC, inactivation of a DNA mismatch repair enzyme, would be useful in identifying HNPCC probands. Monoclonal antibodies against hMLH1 and hMSH2, two DNA mismatch repair proteins which account for most HNPCC cancers, are commercially available. This study sought to investigate the potential utility of these antibodies in determining the expression status of these proteins in paraffin-embedded formalin-fixed tissue and to identify key technical protocol components associated with successful staining. A set of 20 colorectal carcinoma cases of known hMLH1 and hMSH2 mutation and expression status underwent immunoperoxidase staining at multiple institutions, each of which used their own technical protocol. Staining for hMSH2 was successful in most laboratories while staining for hMLH1 proved problematic in multiple labs. However, a significant minority of laboratories demonstrated excellent results including high discriminatory power with both monoclonal antibodies. These laboratories appropriately identified hMLH1 or hMSH2 inactivation with high sensitivity and specificity. The key protocol point associated with successful staining was an antigen retrieval step involving heat treatment and either EDTA or citrate buffer. This study demonstrates the potential utility of immunohistochemistry in detecting HNPCC probands and identifies key technical components for successful staining.

[Histological margin and residual disease assessment for breast carcinoma]

Margin and histological size of ductal in situ carcinoma or intraductal component of an infiltrative carcinoma are important prognostic factors to predict presence/absence as well as amount of residual tumor burden. Their evaluation requires standardized pathological analysis. These factors should be interpreted in clinical and radiological context.

The SMAD4 protein and prognosis of pancreatic ductal adenocarcinoma

PURPOSE

SMAD4 (also called Dpc4) is a tumor suppressor in the TGF-beta signaling pathway that is genetically inactivated in approximately 55% of all pancreatic adenocarcinomas. We investigated whether prognosis after surgical resection for invasive pancreatic adenocarcinoma is influenced by SMAD4 status.

EXPERIMENTAL DESIGN

Using immunohistochemistry, we characterized the SMAD4 protein status of 249 pancreatic adenocarcinomas resected from patients who underwent pancreaticoduodenectomy (Whipple resection) at The Johns Hopkins Hospital, Baltimore, MD, between 1990 and 1997. The SMAD4 gene status of 56 of 249 (22%) pancreatic carcinomas was also determined. A multivariate Cox proportional hazards model assessed the relative risk of mortality associated with SMAD4 status, adjusting for known prognostic variables.

RESULTS

Patients with pancreatic adenocarcinomas with SMAD4 protein expression had significantly longer survival (unadjusted median survival was 19.2 months as compared with 14.7 months in patients with pancreatic cancers lacking SMAD4 protein expression; P = 0.03). This SMAD4 survival benefit persisted after adjustment for prognostic factors including tumor size, margins, lymph node status, pathological stage, blood loss, and use of adjuvant chemoradiotherapy. The relative hazard of mortality for cancers lacking SMAD4 after adjusting for other prognostic factors was 1.36 (95% confidence interval, 1.01-1.83; P = 0.04).

CONCLUSION

Patients undergoing Whipple resection for pancreatic adenocarcinoma survive longer if their cancers express SMAD4.

Mesothelin is overexpressed in the vast majority of ductal adenocarcinomas of the pancreas: identification of a new pancreatic cancer marker by serial analysis of gene expression (SAGE)

PURPOSE

Effective new markers of pancreatic carcinoma are urgently needed. In a previous analysis of gene expression in pancreatic adenocarcinoma using serial analysis of gene expression (SAGE), we found that the tag for the mesothelin mRNA transcript was present in seven of eight SAGE libraries derived from pancreatic carcinomas but not in the two SAGE libraries derived from normal pancreatic duct epithelial cells. In this study, we evaluate the potential utility of mesothelin as a tumor marker for pancreatic adenocarcinoma.

EXPERIMENTAL DESIGN

Mesothelin mRNA expression was evaluated in pancreatic adenocarcinomas using reverse-transcription PCR (RT-PCR) and in situ hybridization, whereas mesothelin protein expression was evaluated by immunohistochemistry.

RESULTS

Using an online SAGE database (http://www.ncbi.nlm.gov/SAGE), we found the tag for mesothelin to be consistently present in the mesothelioma, ovarian cancer, and pancreatic cancer libraries but not in normal pancreas libraries. Mesothelin mRNA expression was confirmed by in situ hybridization in 4 of 4 resected primary pancreatic adenocarcinomas and by RT-PCR in 18 of 20 pancreatic cancer cell lines, whereas mesothelin protein expression was confirmed by immunohistochemistry in all 60 resected primary pancreatic adenocarcinomas studied. The adjacent normal pancreas in these 60 cases did not label, or at most only rare benign pancreatic ducts showed weak labeling for mesothelin.

CONCLUSIONS

Mesothelin is a new marker for pancreatic adenocarcinoma identified by gene expression analysis. Mesothelin overexpression in pancreatic adenocarcinoma has potential diagnostic, imaging, and therapeutic implications.

STK11/LKB1 Peutz-Jeghers gene inactivation in intraductal papillary-mucinous neoplasms of the pancreas

Despite the growing awareness of intraductal papillary-mucinous neoplasms (IPMNs) of the pancreas among clinicians, the molecular features of IPMNs have not been well characterized. Previous reports suggest that inactivation of the STK11/LKB1, a tumor-suppressor gene responsible for Peutz-Jeghers syndrome (PJS), plays a role in the pathogenesis of gastrointestinal hamartomas as well as several cancers, including pancreatic adenocarcinoma. Using polymerase chain reaction amplification of five microsatellite markers from the 19p13.3 region harboring the STK11/LKB1 gene, we analyzed DNA from 22 IPMNs for loss of heterozygosity (LOH). LOH at 19p13.3 was identified in 2 of 2 (100%) IPMNs from patients with PJS and 5 of 20 (25%) from patients lacking features of PJS (7 of 22, 32% overall). Sequencing analysis of the STK11/LKB1 gene in these IPMNs with LOH revealed a germline mutation in one IPMN that arose in a patient with PJS and a somatic mutation in 1 of the 20 sporadic IPMNs. None of the 22 IPMNs showed hypermethylation of the STK11/LKB1 gene. These results suggest that the STK11/LKB1 gene is involved in the pathogenesis of some IPMNs.

Discovery of new markers of cancer through serial analysis of gene expression: prostate stem cell antigen is overexpressed in pancreatic adenocarcinoma

Serial analysis of gene expression (SAGE) can be used to quantify gene expression in human tissues. Comparison of gene expression levels in neoplastic tissues with those seen in nonneoplastic tissues can, in turn, identify novel tumor markers. Such markers are urgently needed for highly lethal cancers like pancreatic adenocarcinoma, which typically presents at an incurable, advanced stage. The results of SAGE analyses of a large number of neoplastic and nonneoplastic tissues are now available online, facilitating the rapid identification of novel tumor markers. We searched an online SAGE database to identify genes preferentially expressed in pancreatic cancers as compared with normal tissues. SAGE libraries derived from pancreatic adenocarcinomas were compared with SAGE libraries derived from nonneoplastic tissues. Three promising tags were identified. Two of these tags corresponded to genes (lipocalin and trefoil factor 2) previously shown to be overexpressed in pancreatic carcinoma, whereas the third tag corresponded to prostate stem cell antigen (PSCA), a recently discovered gene thought to be largely restricted to prostatic basal cells and prostatic adenocarcinomas. PSCA was expressed in four of the six pancreatic cancer SAGE libraries, but not in the libraries derived from normal pancreatic ductal cells. We confirmed the overexpression of the PSCA mRNA transcript in 14 of 19 pancreatic cancer cell lines by reverse transcription-PCR, and using immunohistochemistry, we demonstrated PSCA protein overexpression in 36 of 60 (60%) primary pancreatic adenocarcinomas. In 59 of 60 cases, the adjacent nonneoplastic pancreas did not label for PSCA. PSCA is a novel tumor marker for pancreatic carcinoma that has potential diagnostic and therapeutic implications. These results establish the validity of analyses of SAGE databases to identify novel tumor markers.

Determination of microsatellite instability, p53 and K-RAS mutations in hepatic metastases from patients with colorectal cancer: relationship with response to 5-fluorouracil and survival

In vitro and clinical studies have suggested that high-frequency microsatellite instability (MSI-H) phenotype, p53 and K-ras mutations might influence the response to chemotherapy in a variety of tumors, including primary colorectal cancers (CRC). Unresectable hepatic metastases from CRC are commonly treated with 5-fluorouracil (5FU) and folinic acid. Since several new active drugs are now used for treating CRC, molecular determinants predictive to response to 5FU would thus be crucial for optimizing indications of chemotherapy to those patients. MSI-H phenotype, p53 and K-ras status were characterized in a prospective study of 56 patients with CRC metastatic to the liver and treated with 5FU-based chemotherapy. The objective response rate after a 3-month treatment was 32.1%. The prevalence of p53 mutations, K-ras mutations and MSI-H phenotype was 62.5%, 30.3% and 1.8%, respectively. No significant association was found between response to chemotherapy and p53 mutations (78% mutated tumors in responders vs. 55% in nonresponders; p = 0.10) and K-ras mutations (39% mutated tumors in responders vs. 26% in nonresponders; p = 0.34). Survival was longer for patients with p53-mutated metastases than for patients with unresected wild-type p53 metastases (median survival 15 months vs. 17 months; p = 0.06). The determination of the MSI-H phenotype, p53 and K-ras status in hepatic metastases from CRC does not discriminate a group of patients that should preferentially benefit from 5FU-based chemotherapy. The prognosis of patients with treated liver metastases is better when p53 is mutated.

Determination of microsatellite instability, p53 and K-RAS mutations in hepatic metastases from patients with colorectal cancer: relationship with response to 5-fluorouracil and survival

In vitro and clinical studies have suggested that high-frequency microsatellite instability (MSI-H) phenotype, p53 and K-ras mutations might influence the response to chemotherapy in a variety of tumors, including primary colorectal cancers (CRC). Unresectable hepatic metastases from CRC are commonly treated with 5-fluorouracil (5FU) and folinic acid. Since several new active drugs are now used for treating CRC, molecular determinants predictive to response to 5FU would thus be crucial for optimizing indications of chemotherapy to those patients. MSI-H phenotype, p53 and K-ras status were characterized in a prospective study of 56 patients with CRC metastatic to the liver and treated with 5FU-based chemotherapy. The objective response rate after a 3-month treatment was 32.1%. The prevalence of p53 mutations, K-ras mutations and MSI-H phenotype was 62.5%, 30.3% and 1.8%, respectively. No significant association was found between response to chemotherapy and p53 mutations (78% mutated tumors in responders vs. 55% in nonresponders; p = 0.10) and K-ras mutations (39% mutated tumors in responders vs. 26% in nonresponders; p = 0.34). Survival was longer for patients with p53-mutated metastases than for patients with unresected wild-type p53 metastases (median survival 15 months vs. 17 months; p = 0.06). The determination of the MSI-H phenotype, p53 and K-ras status in hepatic metastases from CRC does not discriminate a group of patients that should preferentially benefit from 5FU-based chemotherapy. The prognosis of patients with treated liver metastases is better when p53 is mutated.

Topoisomerase I-DNA covalent complexes in human colorectal cancer xenografts with different p53 and microsatellite instability status: relation with their sensitivity to CTP-11

The topoisomerase I poison CPT-11 has proved efficient for the treatment of untreated metastatic colorectal cancers (CRC) and those refractory to fluoropyrimidines. However, the interpatient variability is important. A previous in vitro study suggested that measurements of the level of topoisomerase I-DNA intermediates trapped by camptothecin may be useful to estimate the chemosensitivity of colon carcinoma cell lines. To verify this hypothesis, we developed an immuno-assay to detect covalent topoisomerase I-DNA complexes in a series of human colorectal cancers xenografted in nude mice. Six human CRCs were selected for their distinctive p53 and microsatellite instability (MSI) status. Tumour lysates, prepared from mice untreated or treated with CPT-11, were fractionated onto CsCl gradients to separate free and DNA-bound topoisomerase I by centrifugation. Interestingly, significant levels of DNA-topoisomerase I complexes were detected in the tumours most responsive to the treatment with CPT-11, irrespective of their MSI and p53 phenotypes. Our in vivo study fully agrees with the predictions from the in vitro data indicating that evaluation of topoisomerase I-DNA complexes would be useful to predict the response of CRC to a treatment with CPT-11.

Association of a duodenal follicular lymphoma and hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC) is an inherited predisposition to colorectal and endometrial cancers caused by germline mutation of mismatch repair genes, with hMLH1 and hMSH2 underlying the majority of the cases. Although lymphoid tumors are the most common tumors in mouse models for HNPCC, lymphomas are almost never encountered in patients who have HNPCC, except in rare families with germline homozygous deletion of hMLH1. We report the case of a 53-year-old man who had a history of colon cancers related to constitutional hMLH1 mutation and who was diagnosed as having a duodenal follicular lymphoma This diagnosis was supported by IgH-BCL2 rearrangement and BCL2 immunoreactivity in tumor cells. The association of both of these possibly related rare diseases has never been reported. To clarify this relationship, we searched for hMLH1 expression and mismatch repair deficiency in the duodenal lymphoma. hMLH1 immunostaining was positive in lymphoid tumor cells, and no microsatellite instability was detected. In agreement with mouse models for HNPCC, these results suggest the involvement of alternative mechanisms to complete mismatch repair deficiency for lymphomagenesis in HNPCC syndrome.

Sensitivity to CPT-11 of xenografted human colorectal cancers as a function of microsatellite instability and p53 status

Biological parameters influencing the response of human colorectal cancers (CRCs) to CPT-11, a topoisomerase 1 (top1) inhibitor, were investigated using a panel of nine CRCs xenografted into nude mice. CRC xenografts differed in their p53 status (wt or muf) and in their microsatellite instability phenotype (MSI+ when altered). Five CRC xenografts were established from clinical samples. All five had a functional p53, two were MSI+ and three were MSI-. Tumour-bearing nude mice were treated intraperitonealy (i.p.) with CPT-11. At 10 mg kg(-1) of CPT-11, four injections at 4-day intervals, four of the five xenografts responded to CPT-11 (growth delay of up to 10 days); the non-responder tumour was MSI-. At 40 mg kg(-1) of CPT-11, six injections at 4-day intervals, the five CRCs displayed variable but marked responses with complete regressions. In order to assess the role of p53 status in CPT-11 response, four CRC lines were used. HT29 cell line was MSI-/Ala273-mutp53, its subclone HT29A3 being transfected by wtp53. LoVo cell line was MSI+/wtp53, its subclone X17LoVo dominantly expressed Ala273-mutp53 after transfection. LoVo tumours (MSI+/mutp53) were more sensitive than X17LoVo (MSI+/mutp53. HT 29 tumours (MSI-Imutp53), were refractory to CPT-11 while HT29A3 tumours (MSI-/wtp53) were sensitive, showing that wtp53 improves the drug-response in these MSI- tumours. Levels of mRNA expression of top1, fasR, TP53 and mdr1 were semi-quantified by reverse transcription polymerase chain reaction. None of these parameters correlated with CPT-11 response. Taken together, these observations indicate that MSI and p53 alterations could be associated with different CPT-11 sensitivities; MSI phenotype moderately influences the CPT-11 sensitivity, MSI+ being more sensitive than MSI(-)CRC freshly obtained from patients, mutp53 status being associated with a poor response to CPT-11.

[Endometrial stromal tumor associated with rhabdoid phenotype and and zones of "sex cord-like" differentiation]

An unusual endometrial stromal sarcoma is described in a 50-year-old patient. The distinctive feature of this case is the focal occurrence of sex cord-like pattern and rhabdoid appearance of tumor cells. Rhabdoid cells have an eosinophilic cytoplasm and a vesicular nucleus with a prominent nucleolus. Immunohistochemistry showed positive cytoplasmic staining for both cytokeratin and vimentin, and ultrastructural examination identified tumor cells with abundant cytoplasmic intermediate filaments. To our knowledge, only one case of endometrial stromal sarcoma with this unusual morphological association has been reported in the literature.

Cytogenetic and molecular analysis of a t(1;22)(p36;q11.2) in a rhabdoid tumor with a putative homozygous deletion of chromosome 22

Malignant rhabdoid tumors are rare and aggressive neoplasms of childhood, occurring in the kidney or in various extrarenal locations. Most cytogenetic studies of these tumors have shown the frequent involvement of chromosome 22, including translocations and/or deletions, with a critical region for a rhabdoid tumor gene mapping to chromosome segment 22q11, close to BCR. We report a case of an extrarenal rhabdoid tumor with a t(1;22)(p36;q11.2) that was associated with deletions of chromosomes 1 and 22. We have performed fluorescence in situ hybridization to bracket the translocation breakpoints on both chromosomes and microsatellite analysis to establish the deletion of chromosome 22 more precisely. The chromosome 22 translocation breakpoint is localized close to BCR, in the region covered by the overlapping YACs 446B5 and 361D9, and it is associated with a proximal hemizygous deletion of approximatively 2 Mb. On chromosome 1, the translocation breakpoint maps to a 25 cM region, proximal to D1Z2 and distal to PND, and is also associated with an estimated deletion of 8 Mb. Moreover, microsatellite analysis has demonstrated a homozygous deletion of chromosome 22 for three contiguous loci, immediately distal to BCR. This result suggests that a tumor suppressor gene involved in rhabdoid tumor oncogenesis could be localized in this region of chromosome 22.