DNA Mismatch Repair-Deficient Colorectal Carcinoma: Referral Rate for Genetic Cancer Risk Assessment in a Brazilian Cancer Center

BACKGROUND

Approximately 15% of colorectal cancers (CRCs) are deficient in DNA mismatch repair proteins (dMMR), a characteristic that can occur in both sporadic and hereditary CRC. Due to sparse studies on dMMR CRC in the Brazilian population, we conducted a retrospective analysis of referral rates for Genetic Cancer Risk Assessment of this population and also describing clinical and molecular characterization of these tumors.

METHODS

A retrospective, longitudinal, and unicenter study that included patients with dMMR CRC detected by IHC analysis from Pathology Database of our institution, from January 2015 to July 2017.

RESULTS

MMR IHC testing was performed in 998 CRC tumors, and 78 tumors (7.8%) had dMMR. The mean age at diagnosis was 56.8 years (17-90), and most patients were female (41 out of 78, 52.6%). Of the 52 patients with right-sided CRC, 40 tumors (77%) had loss of the MLH1 and/or PMS2 expression, and 12 tumors (23%) had loss of MSH2 and/or MSH6 expression (p = 0.005). From 78 patients with dMMR CRC, only 43 patients (55.1%) were referred for genetic counseling (GC), and of them, only 33 patients (76.7%) really went to GC consultation. A total of 21 patients with dMMR CRC performed genetic testing.

CONCLUSION

Overall, genetic referral was less than expected in our population. Most of dMMR CRC patients did not receive GC, even in a cancer center, either due to the absence of referral or personal decision and few patients who pursued genetic counseling performed genetic testing.

Aberrant expression of RSK1 characterizes high-grade gliomas with immune infiltration

The p90 ribosomal S6 kinase (RSK) family, a downstream target of Ras/extracellular signal-regulated kinase signaling, can mediate cross-talk with the mammalian target of rapamycin complex 1 pathway. As RSK connects two oncogenic pathways in gliomas, we investigated the protein levels of the RSK isoforms RSK1-4 in nontumoral brain (NB) and grade I-IV gliomas. When compared to NB or low-grade gliomas (LGG), a group of glioblastomas (GBMs) that excluded long-survivor cases expressed higher levels of RSK1 (RSK1hi ). No difference was observed in RSK2 median-expression levels among NB and gliomas; however, high levels of RSK2 in GBM (RSK2hi ) were associated with worse survival. RSK4 expression was not detected in any brain tissues, whereas RSK3 expression was very low, with GBM demonstrating the lowest RSK3 protein levels. RSK1hi and, to a lesser extent, RSK2hi GBMs showed higher levels of phosphorylated RSK, which reveals RSK activation. Transcriptome analysis indicated that most RSK1hi GBMs belonged to the mesenchymal subtype, and RSK1 expression strongly correlated with gene expression signature of immune infiltrates, in particular of activated natural killer cells and M2 macrophages. In an independent cohort, we confirmed that RSK1hi GBMs exclude long survivors, and RSK1 expression was associated with high protein levels of the mesenchymal subtype marker lysosomal protein transmembrane 5, as well as with high expression of CD68, which indicated the presence of infiltrating immune cells. An RSK1 signature was obtained based on differentially expressed mRNAs and validated in public glioma datasets. Enrichment of RSK1 signature followed glioma progression, recapitulating RSK1 protein expression, and was associated with worse survival not only in GBM but also in LGG. In conclusion, both RSK1 and RSK2 associate with glioma malignity, but displaying isoform-specific peculiarities. The progression-dependent expression and association with immune infiltration suggest RSK1 as a potential progression marker and therapeutic target for gliomas.

Survival of gastric cancer (GC) patients is not determined by the predominant genomic ancestry (PGA): Results from an ethnically admixed Brazilian cohort of GC patients

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Background: Clinical characteristics, treatment response and overall survival of GC patients differ between Asian and non-Asian countries. Here we evaluated the possible associations between PGA, clinical characteristics and survival in an admixed GC Brazilian cohort. Methods: We included 112 GC pts diagnosed and treated at AC Camargo Cancer Center (São Paulo, Brazil) before 2013. The study was approved by local IRB. Genomic DNA was used for capture-based enrichment of a customized gene panel including 99 genes. Libraries were sequenced in the NextSeq 500 platform (Illumina), using paired-end reads (2x75bp). Ancestries were determined through a set of ancestry informative markers (AIMs), covered by target and off-target reads, described by Elhaik et al. (2014). Results: An average of 406 AIMs were recovered from the available samples, revealing average ancestries was as follows: 55.4% European, 27.7% Asian, 8.9% African; 8% of subjects were highly admixed (HA; < 50% of any ancestry). We found no association between PGA and age at diagnosis (p = 0.58), tumor location (p = 0.34), Lauren (p = 0.24) and staging (p = 0.68). There was an association between PGA and gender (p = 0.04) and a marginal association between PGA and EBV (p = 0.056). BRCA2 was the only gene enriched in the Asian subgroup, compared to the other groups combined (p = 0.009). The median follow-up time was 95 months. We found no differences in median overall survival (OS) (p = 0.4) or disease-free survival (DFS) (p = 0.6) according to PGA. The HA subgroup presented worst survival outcomes compared to the other groups aggregated (mOS 34m; 95%CI 5-80 x mOS 71m; 95% CI 44-85, respectively), but the difference was not statistically significant (HR 1,73; 95% CI 0.74-4.05; p = 0.2). Even for patients with > 75% AIMs for any given ancestry, we found no differences in OS between Europeans (n = 25; mOS 86m; 95%CI 80-NA), Asians (n = 22; mOS 83m; 95%CI 51-NA) and Africans (n = 5; mOS 67m; 95%CI 22-NA), p = 0.4. Conclusions: The most prevalent ancestries in this Brazilian GC cohort were European, followed by Asian and African. Although we found associations between ancestry and a few clinical aspects, PGA was not associated with survival.

Disassociation of ARID1A with genomic ancestry and prognostic impact in an admixed cohort of Brazilian patients with gastric cancer (GC)

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Background: Loss of expression of ARID1A, a tumor suppressor gene involved in chromatin remodeling and transcription activation, has been associated with worse prognosis in Asian GC patients (Yang et al. 2016). Mutations in ARID1A have been found in 8-27% of GC, usually leading to gene/protein inactivation. Here we evaluated the possible involvement of ARID1A mutations and clinical characteristics, while considering genomic ancestry and survival, in a cohort of Brazilian GC patients. Methods: We included 112 pts diagnosed with GC and treated at AC Camargo Cancer Center before 2013. The study was approved by local IRB. Genomic DNA was used for capture-based enrichment of a customized gene panel including 99 genes. Libraries were sequenced in the NextSeq 500 platform (Illumina), using paired-end reads (2x75bp). For ancestry inference we used a set of ancestry informative markers, covered by target and off-target reads, described by Elhaik et al. (2014). Results: Median age was 64y (37-91), 63% were male, M:F ratio was 1.73. Most cases were classified as Diffuse (47.3%) followed by Intestinal (41.1%), Mixed (2.7%) and 8.9% were deemed unclassifiable by Lauren´s classification. 22.3% were stage I, 20.5% stage II, 42.9% stage III and 14.3% stage IV. 11.6% were in the GEJ and 80.4% were in corpus/antrum. Five patients were EBV positive (4.5%). Genomic ancestry was as follows: 55.4% European, 27.7% Asian, 8.9% African and 8% were highly admixed ( < 50% of any ancestry). ARID1A was mutated in 19% of cases and showed no association with age at diagnosis (p = 0.21), gender (p = 0.76), tumor location (p = 0.55), staging (p = 0.42), Lauren (p = 0.14) or EBV (p = 0.42). ARID1A had no impact on overall survival (OS) (HR 1.17; 95%CI 0.59-2.31; p = 0.6) or disease-free survival (DFS) (HR 1.24; 95%CI 0.66-2.32; p = 0.5), including the subgroup with Asian genomic background: OS-Asia (HR 1.08; 95%CI 0.31-3.81; p = 0.9), DFS-Asia (HR 1.15; 95%CI 0.32-4.12; p = 0.8). Conclusions: ARID1A is a common driver in GC among Brazilian patients. Unlike in Asians, ARID1A was not prognostic in this Brazilian cohort even in the subgroup with a predominant ( > 50%) Asian genomic ancestry.

Mutation Detection in Tumor-Derived Cell Free DNA Anticipates Progression in a Patient With Metastatic Colorectal Cancer

Background: The observation of tumor-derived cell-free DNA (ctDNA) in plasma brought new expectations to monitor treatment response in cancer patients.

Case presentation: In an exploratory case of a 57-year-old man diagnosed with metastatic sigmoid adenocarcinoma, we used a hotspot panel of cancer-associated gene mutations to identify tumor-specific mutations in the primary tumor and metastasis. Results: Five mutations were detected (KRAS, p.Gly12Val; TP53, p.Arg175His; RB1, p.Ile680Thr; ALK, p.Gly1184Glu; and ERBB2, p.Lys860Lys), of which three were detected in both tissue types (primary tumor and metastasis). All five mutations were monitored in the ctDNA of six serial plasma samples. Only KRAS and TP53 mutations were detected at a high frequency in the first plasma sample. After 1 month of chemotherapy the allele frequencies of both mutations fell below the detection limit. From the third month of systemic treatment onward, the allele frequencies of both mutations were detectable in plasma, displaying a continual increase thereafter. The remaining three mutations were not detected in plasma samples. Signs of disease progression in ctDNA during the treatment period were evident while computed tomography (CT) measurements suggested stable metastatic lesions throughout the treatment.

Conclusions: Liquid biopsies revealed tumor heterogeneity and predicted tumor progression, demonstrating the potential of ctDNA analysis to be a sensitive and specific tool for monitoring treatment responsivity and for early identification of treatment resistance.

Evaluation of the outcome of adjuvant treatment for gastric cancer in Brazil and Peru: A retrospective study in two cancer centers in Latin America

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Background: Gastric cancer (GC) is one of the most frequent malignancies in developing countries. In Peru, it is the fourth most incident cancer, and the sixth one in Brazil. Mortality is still high. The chance of relapse of patients with non-metastatic disease undergoing surgery is more than 50%. It is suspected that Latin American patients present worse evolution compared to those treated in Asia or in developed countries, therefore it is fundamental to study factors related to the prognosis and evolution of patients with GC in our continent. We aimed to evaluate the outcome of adjuvant treatment for GC in patients from two countries with different racial miscegenation and eating habits, and correlate this with clinicopathological features. Methods: We retrospectively analyzed 187 patients with GC who underwent curative surgery and received CRT at AC Camargo Cancer Center (ACCCC) in Brazil and Instituto Nacional de Enfermedades Neoplasicas (INEN) in Peru. CRT was defined as MacDonald protocol. Primary endpoint was overall survival (OS). Cox regression model was performed in order to calculate hazard ratio (HR) and 95% confidence intervals (95%CI). Results: Median follow up time was 51 and 20 months in Brazil and Peru, respectively. Median age of our cohort was 54 years-old. Male sex was predominant in both countries (Brazil: 54.7%; Peru: 56.9%). Diffuse subtype also was predominant (Brazil: 58.3%; Peru: 55.1%). Median OS was 103.9 and 45.2 months in Brazil and Peru respectively (p < 0.001). In the multiple analysis, we found that pathological stage (I/II vs. III; HR = 4.1, 95%CI 1.4-11.7; p = 0.009) was independent prognostic factor adjusted by country of treatment, histological subtype, localization, age and gender. Conclusions: Survival differences exist between Brazil and Peru. We observed that patients from Peru had more advanced pathological stage after surgery. This difference suggests a possible prognostic factor in OS. Ethnic/genetic factors, eating habits and other clinicopathological or molecular factors may also explain different prognosis. Future studies are warranted to determine these prognostic factors in Latin American gastric cancer patients.

EGFR amplification and expression in oral squamous cell carcinoma in young adults

The aim of this study was to investigate epidermal growth factor receptor (EGFR) gene alterations in two groups of patients with oral squamous cell carcinoma (OSCC) (a test group of subjects aged ≤40 years and a control group of subjects aged ≥50 years) and to associate the results with EGFR immunostaining, clinicopathological features, and the prognosis. Sixty cases of OSCC were selected (test group, n=21; control group, n=39). The tissue microarray technique was applied to ensure the uniformity of results. Gene amplification was analyzed by fluorescence in situ hybridization (FISH), and immunohistochemical staining for EGFR was analyzed using an automated imaging system. EGFR amplification was higher in the test group than in the control group (P=0.018) and was associated with advanced clinical stage (P=0.013), regardless of age. Patients with EGFR overexpression had worse survival rates, as did patients who had T3-T4 tumours and positive margins. EGFR overexpression has a negative impact on disease progression. Despite the higher amplification of EGFR in young adults, it does not significantly impact the survival rates of affected patients.

Tissue-Associated Bacterial Alterations in Rectal Carcinoma Patients Revealed by 16S rRNA Community Profiling

Sporadic and inflammatory forms of colorectal cancer (CRC) account for more than 80% of cases. Recent publications have shown mechanistic evidence for the involvement of gut bacteria in the development of both CRC-forms. Whereas, colon and rectal cancer have been routinely studied together as CRC, increasing evidence show these to be distinct diseases. Also, the common use of fecal samples to study microbial communities may reflect disease state but possibly not the tumor microenvironment. We performed this study to evaluate differences in bacterial communities found in tissue samples of 18 rectal-cancer subjects when compared to 18 non-cancer controls. Samples were collected during exploratory colonoscopy (non-cancer group) or during surgery for tumor excision (rectal-cancer group). High throughput 16S rRNA amplicon sequencing of the V4-V5 region was conducted on the Ion PGM platform, reads were filtered using Qiime and clustered using UPARSE. We observed significant increases in species richness and diversity in rectal cancer samples, evidenced by the total number of OTUs and the Shannon and Simpson indexes. Enterotyping analysis divided our cohort into two groups, with the majority of rectal cancer samples clustering into one enterotype, characterized by a greater abundance of Bacteroides and Dorea. At the phylum level, rectal-cancer samples had increased abundance of candidate phylum OD1 (also known as Parcubacteria) whilst non-cancer samples had increased abundance of Planctomycetes. At the genera level, rectal-cancer samples had higher abundances of Bacteroides, Phascolarctobacterium, Parabacteroides, Desulfovibrio, and Odoribacter whereas non-cancer samples had higher abundances of Pseudomonas, Escherichia, Acinetobacter, Lactobacillus, and Bacillus. Two Bacteroides fragilis OTUs were more abundant among rectal-cancer patients seen through 16S rRNA amplicon sequencing, whose presence was confirmed by immunohistochemistry and enrichment verified by digital droplet PCR. Our findings point to increased bacterial richness and diversity in rectal cancer, along with several differences in microbial community composition. Our work is the first to present evidence for a possible role of bacteria such as B. fragilis and the phylum Parcubacteria in rectal cancer, emphasizing the need to study tissue-associated bacteria and specific regions of the gastrointestinal tract in order to better understand the possible links between the microbiota and rectal cancer.

Evaluation of RB Gene and Cyclin-Dependent Kinase Inhibitors P21 and P27 in Pleomorphic Xantoastrocytoma

Pleomorphic xantoastrocytoma (PXA) is a rare, circumscribed astrocytic tumor that usually occurs in the superficial cerebral hemispheres in children and young adults. Most patients have a favorable prognosis, but recurrence and malignant transformation have been reported. In diffuse gliomas, approximately one third demonstrate mutations of the RB gene. Low expression level and high activity of p27 are known to constitute an independent prognostic factor in patients with malignant gliomas, while p21 expressions have variable labeling ranges. The molecular and genetic basis for tumorigenesis and progression of PXA are still largely unknown. In this study, 13 PXAs were examined immunohistochemically for pRb, p21, and p27 expression. Nine PXAs expressed homogeneous pRb positivity in the most nuclei of the tumor cells. Four cases showed an abnormal pRb staining pattern. All PXAs were positive for nuclear expression of p21. Diffuse nuclear positivity of p27 was seen in 10 cases, focal in 2, and in 1 case was not present. The cases with focal and negative p27 nuclear expression had few pRb-positive nuclei. The majority of PXAs appear to have preserved pRb, p21, and p27 functions. Additional studies are necessary to investigate whether cases with altered pRb and p27 expressions are associated with increased risk of recurrence or malignant transformation.

Evaluation of NF2 Gene Deletion in Pediatric Meningiomas Using Chromogenic In Situ Hybridization

Meningiomas are uncommon childhood tumors. They could be of significant size at presentation, which has been associated with difficult surgical excision, high recurrence rate, and possibly aggressive clinical behavior. Monosomy 22 is a common molecular event in this neoplasm. Additionally, losses on chromosomes 1,7,10, and 14 have been identified in clinically aggressive meningiomas. Using chromogenic in situ hybridization, we studied a group of pediatric meningiomas, including neurofibromatosis type II—associated, sporadic, and radiation-induced cases. We found NF2 gene deletion in about 72% of the cases, with corresponding absent or minimal merlin protein expression by immunohistochemistry. Our findings confirm that the NF2 gene plays a role in the tumorigenesis of pediatric meningiomas and that chromogenic in situ hybridization is an efficient, economic, and reliable method for routinely assessing NF2 gene deletion in formalin-fixed, paraffin-embedded tissues.

Value of mismatch repair deficiency for predicting complete pathologic response to preoperative chemoradiation in rectal carcinoma

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Background: The objective of this study is to investigate the value of mismatch repair deficiency (MMR) in rectal cancers as a predictive fator of response to chemoradiation in rectal cancer. Methods: We evaluated a consecutive cohort of 109 patients with locally advanced rectal carcinomas, treated with a total dose of 5,040 cGy of preoperative radiation therapy, concomitant with infusional 5-FU-based chemotherapy. Radical surgery (TME) was performed in all patients. MMR status was determined by imunohistochemistry in tumor tissue from biopsies prior to chemoradiation. The primary endpoint was complete pathologic response (pCR). Results: 63 patients (57.8%) were male, and the mean age was 60 years (range from 28 to 93). The rate of pCR was 18.3%. Among clinical variables (age, sex, distance to dentate line, per-treatment CEA level, and clinical assessment of response), only clinical complete response (cCR) was significant associated with cPR (p=0.009). Only two patients (1.8%) presented tumors with MMR deficiency. These 2 patients had cPR. Despite the very low rate of MMR deficiency, the association with cPR was significant (p=0.032). Conclusions: Considering the low rate of MMR deficiency found, we do not consider MMR status as a good tool for predicting pathologic response to chemoradiation in rectal cancer. Further investigation can be considered among the subgroup of Lynch syndrome patients.

Abstract B36: Expression of growth and cell proliferation factors in gastric carcinomas: The association with poor overall survival on patients with intestinal type

Background: Gastric carcinomas (GC) express a variety of growth factors and cell proliferation acting in the mechanisms of tumor invasion and spread. The expression of angiogenic factors such as vascular endothelial growth factor (VEGF) has been demonstrated in diffuse type GC, whereas expression of growth factors is associated with intestinal-type carcinomas. Objective: To study the immunohistochemical expression of proteins associated with growth factors and cell proliferation in GC. Methods: We studied 400 GC, arranged in duplicates in 2 blocks of tissue microarray (TMA). Immunohistochemistry was performed using antibodies: c-MET (Novocastra), TGFbetaI (Santa Cruz), TGFbetaII (Santa Cruz), c-erbB-2 (Dako) and VEGF (Santa Cruz). Cases were considered positive for TGFbetaI, TGFbetaII and VEGF when cytoplasmic staining was observed in more than 10% of tumor cells. Positive cases for c-met and c-erbB-2 were detected when strong staining on the membrane cells was observed in more than 10% of neoplastic cells. Results: Expression of TGFbetaI, TGFbetaII and VEGF were detected in 314/385 (81%), 370/382 (96%) and 333/366 (90%) of GC. 333/376 (88%) cases were positive for c-met and 54/385 (14%) for c-erbB-2. Intestinal type carcinomas were more often positive for TGFbetaII (p = 0.01), VEGF (p = 0.001), c-met (p = 0.01), and c-erbB-2 (p = 0.001). According to univariate statistical analyzes expressions of TGFbeta II, c-met and c-erbB-2 were independent factors associated with overall survival of patients with GC. Conclusions: The proteins associated with growth factors and cell proliferations are differentially expressed in intestinal type of GC. Our findings pointed them out as biological factors associated with worse prognosis and important therapeutic targets.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B36.

Citation Format: Maria D. Begnami, Clovis AL Pinto, Sueli Nonogaki, Fernando Soares, Luiz GCA Lima. Expression of growth and cell proliferation factors in gastric carcinomas: The association with poor overall survival on patients with intestinal type. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B36.

Expression of immunohistochemical markers in ampullary cancer (AC) and association with behavior

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Background: Curiously, the ampulla is formed by the union of two distinct types of mucosa: intestinal (GI) and pancreatobiliary(PB). Based on this fact, ACs could have different biologic behaviors. Methods: Between 1999 and 2012 we performed a retrospective analysis of patients with AC that underwent a pancreaticoduodenectomy (PD) with curative intent in our institution and the expressions of immunohistochemical markers related to GI origin (CK20 and CDX2) and to PB origin: (CK7 and MUC1) and its association with outcomes. Results: Twenty-seven patients underwent (PD), (M:F=15:12), median age was 62 (range33-83), 85.2% had R0 resection, 29.6% had positive lymph-nodes, 44.4% had perineural invasion, 22.2% had vascular invasion, 29.6% had lymphatic invasion, 59.2% had moderately differentiated tumors. AJCC stage pathologic grouping was: I=33.3%, II=37%, III= 29.6%; Median follow-up was 33.8 months. Relapse free survival was 43% in 3 years and overall survival was 53.7% in 5 years. The relapse rate was 59.2% and the majority of these relapses (69%) were distant metastasis without local relapse. Only positive lymph-node status (p=0,004, HR: 5.99) and R1 resection (R1: p=0.015, HR: 8.75) were independent prognostic factors for relapse on multivariate analysis. Among the patients, 21 were evaluated for the expression of immunohistochemical markers. Ten AC were classified into TGI type, 9 into PB type and 2 into unusual. An association between PB type and positive lymph node status (p=0.05) and more advanced stage (p=0.05) was found (Fisher’s exact test). There was no difference in relapse and survival between the histological subtypes, however, more PB patients had received adjuvant therapy. Conclusions: Histological subtypes of AC may have different behavior, but they are frequently neglected during decision of adjuvant therapy.

NOTCH1 as a potential prognostic biomarker for anti-VEGF therapy in patients with metastatic colorectal cancer

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Background: There are no validated biomarkers for clinical response or survival benefit in patients treated with bevacizumab (Bv) in advanced metastatic colorectal cancer (mCRC). The aim of this study was to evaluate the predictive value of putative biomarkers in mCRC. Methods: One hundred and five mCRC patients who received Bv combined with FOLFOX or FOLFIRI were retrospectively evaluated for clinical and pathological characteristics. VEGFR1, VEGFR2, VEGFR3, PlGF, DLL4 and NOTCH1 expression were assessed by immunohistochemistry on formalin-fixed, paraffin-embedded neoplastic tissue of either primary or metastatic tissue in a tissue microarray. High levels of expression were defined as less than or equal to or more than the median. Survival curves were calculated by the Kaplan-Meier method and compared by the log-rank test. For multivariate analysis the Cox proportional hazards model was used. Results: Grade 1 or 2 (p=0.01), non-mucin-producing histology (p=0.04) and presence of liver metastasis (p=0.001) were associated with a higher response rate. There was no difference between the expression of markers and the response rate. ECOG 0 or 1 (p=0.002), grade 1 or 2 (p=0.02), liver metastasis (p=0.003), no lymph node metastasis (p=0.01) no peritoneal metastasis (p=0.02) and resection of metastasis (p<0.001) were correlated with higher progression-free survival (PFS). There was also a strong correlation between ECOG 0 or 1 (p=0.001), grade 1 or 2 (p=0.006), no lymph node metastasis (p=0.004), liver metastasis (p<0.001) and resection of metastasis (p<0.0001) with better overall survival. There was a trend between high expression of NOTCH1 (p=0.06) and worst PFS.High expression of VEGFR2 (p=0.07) was slightly associated with a better overall survival, while high expression of NOTCH1 was associated with a worse overall survival (p=0.01). Using multivariate analysis, NOTCH1 proved to be an independent variable for adverse overall survival (HR 2.01, IC 1.07 – 3.77, p=0.02). Conclusions: High NOTCH1 expression assessed by immunohistochemistry is capable of predicting poor survival in advanced colorectal cancer patients treated with bevacizumab.

Role of clinical variables for predicting pathologic response to neoadjuvant chemoradiation in locally advanced rectal cancer

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Background: pathologic response to neoadjuvant chemoradiation is a strong prognostic factor for rectal cancer. Some studies have suggesting a wait and see approach for rectal cancer after clinical complete response to chemoradiation. In this study, we tried to identify clinical predictive factors of pathologic response to neoadjuvant chemoradiation. Methods: we retrospectively reviewed data of 129 patients from a prospective database, treated between January, 2008 and December, 2012. Patients with mid and low rectal adenocarcinoma, clinically staged (MRI) as T3,T4 any N or any T, N+, received pre-operative chemoradiation, which consists in 5040 cGy, concomitant to 5-FU-based chemotherapy. All patients were operated, by radical TME procedures. The clinical variables analyzed were: age, gender, distance from dentate line, cT stage, cN stage, pre-treatment CEA level, NIH toxicity during chemoradiation, endoscopic assessment of response, and interval between the end of radiation and surgery. We investigate associations between these variables with complete pathological response (cPR) and “good” pathological response (gPR), defined as ypT0orT1 N0. Results: the rate of cPR was 20.2%. The rate of gPR was 31.8%. For predicting cPR, only the endoscopic assessment of response showed significant association with cPR. Among 18 patients with complete endoscopic response, 8 (44.4%) confirmed cPR after resection. Among 93 patients with endoscopic findings suggesting residual disease, 14 (15.1%) presented cPR (p=0.008). 55.6% (10/18) of patients with complete endoscopic response still have microscopic residual disease in the resected specimen. For predicting gPR, only the cN staging was significantly associated with ypT0orT1 N0 (23.9% of gPR among cN+ patients against 41.3% among cN0 patients; p=0.038). Conclusions: clinical tools are very poor for predicting pathological response to neoadjuvant chemoradiation therapy in patients with locally advanced rectal carcinomas. Despite endoscopic assessment of response by retoscopy have showed significant association with cPR, the predictive value was weak.

Expression of growth and cell proliferation factors in gastric carcinomas: The association with poor overall survival on patients with intestinal type

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Background: Gastric carcinomas (GC) express a variety of growth factors and cell proliferation acting in the mechanisms of tumor invasion and spread. The expression of angiogenic factors such as vascular endothelial growth factor (VEGF) has been demonstrated in diffuse type GC, whereas expression of growth factors is associated with intestinal-type carcinomas. Objective: To study the immunohistochemical expression of proteins associated with growth factors and cell proliferation in GC. Methods: We studied 400 GC, arranged in duplicates in 2 blocks of tissue microarray (TMA). Immunohistochemistry was performed using antibodies: c-MET (Novocastra), TGFbetaI (Santa Cruz), TGFbetaII (Santa Cruz), c-erbB-2 (Dako) and VEGF (Santa Cruz). Cases were considered positive for TGFbetaI, TGFbetaII and VEGF when cytoplasmic staining was observed in more than 10% of tumor cells. Positive cases for c-met and c-erbB-2 were detected when strong staining on the membrane cells was observed in more than 10% of neoplastic cells. Results: Expression of TGFbetaI, TGFbetaII and VEGF were detected in 314/385 (81%), 370/382 (96%) and 333/366 (90%) of GC. 333/376 (88%) cases were positive for c-met and 54/385 (14%) for c-erbB-2. Intestinal type carcinomas were more often positive for TGFbetaII (p = 0.01), VEGF (p = 0.001), c-met (p = 0.01), and c-erbB-2 (p = 0.001). According to univariate statistical analyzes expressions of TGFbeta II, c-met and c-erbB-2 were independent factors associated with overall survival of patients with GC. Conclusions: The proteins associated with growth factors and cell proliferations are differentially expressed in intestinal type of GC. Our findings pointed them out as biological factors associated with worse prognosis and important therapeutic targets.

Prognosis and patterns of failure after curative pancreaticoduodenectomy for early-stage ampullary adenocarcinomas

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Background: Ampullary cancer (AC) is a rare malignancy. There is no consensus about the role of adjuvant radiotherapy and chemotherapy, mainly for early-stage tumors. Methods: Between 2007 and 2012 we performed a retrospective analysis of patients with AC that underwent a pancreaticoduodenectomy (PD) with curative intent in our institution. Results: Twenty-four patients underwent (PD), (M:F=13:11), median age was 63 (range35-83), 87% had R0 resection, median of resected lymph-nodes was 8.5 (range 2-30), 29% had positive lymph-nodes, 46% had perineural invasion, 21% had vascular invasion, 29% had lymphatic invasion, 50% had tumors > 2 cm, 54% had moderately differentiated tumors. AJCC stage pathologic grouping was: I=37,5%, II=29%, III=33%; Median follow-up was 27 months, median progression free survival was 29 months and median overall survival was 101 months. Only lymph-node status was independent prognostic factor for disease free survival on multivariate analysis (p=0,045, HR: 7,8). Among patients with early-stage tumors (n=13), only one received adjuvant therapy. The relapse rate was 23% and 50%, for stage I and IIa tumors, respectively. Among the recurrences, 80% of relapses were distant metastasis without local relapse. In patients with stage IIb and III tumors (n=11), 63,6% received adjuvant treatment (57% chemotherapy and 43% radiochemotherapy). The relapse rate was 100% and 75%, respectively, and 66% of these relapses were distant metastasis without local relapse. 75% of patients who had local recurrence had tumors in stage IIb or III. Conclusions: Our study shows a high disease relapse rate in well-operated patients, even in early-stage tumors, with no nodal involvement, mainly with distant disease. The majority of patients who had local relapses had a more advanced stage and systemic relapses associated. This information can help guide decisions on the choice of adjuvant therapy.

HER2 status and histopathologic findings related to tumor regression in gastric carcinomas treated with preoperative chemotherapy

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Background: Neoadjuvant chemotherapy is now the standard of care of patients with resectable gastric carcinomas (GC). Predictive molecular markers and histopathological evidence of tumour response to chemotherapy are not widely available. In this study we evaluated HER2 status and histopathological features associated with tumor regression in 36 GC treated with neoadjuvant chemotherapy followed by surgery.

Methods: 36 patients had received ECF, DCF or ECX chemotherapy prior the surgery. The entire tumor beds of the specimens were histologically evaluated. HER2 expression by immunohistochemistry was detected in the biopsy and gastrectomy specimens.

Results: 46% of the cases were intestinal type, 40% were diffuse and 14% were unclassified. Nine patients had major clinical and radiological response (CRR) characterized by presence of viable tumor cells less than 50% of the tumor with increased fibrosis (>50%). Three cases had complete CRR showing tumor beds totally replaced by fibrosis. The remaining cases had minimal CRR characterized by viable tumor cells in more than 50% and minimal fibrosis. Necrosis was not found; mucinous metaplasia was observed in three cases of the major CRR. Inflammatory infiltrated was found in all cases. The downstaging of T-stage seems to be greater in the intestinal type than diffuse type (80% vs 44%). HER2+ (score 3) was detected in 16,6% of the biopsy specimen. Only 1 case was HER2+ in the biopsy and in the gastrectomy tissue. All the HER2+ GC showed minimal CRR.

Conclusions: The ratio of viable tumor cells and fibrosis is directly associated with tumor response to preoperative chemotherapy. The chemotherapy regimens seem to collaborate to downstaging rates; however the treatment of HER2+ GC group could be improved by the use of Ttrastuzumab.

Identification of protein expression signatures in gastric carcinomas using clustering analysis

BACKGROUND AND AIM

The identification of gastric carcinomas (GC) has traditionally been based on histomorphology. Recently, DNA microarrays have successfully been used to identify tumors through clustering of the expression profiles. Random forest clustering is widely used for tissue microarrays and other immunohistochemical data, because it handles highly-skewed tumor marker expressions well, and weighs the contribution of each marker according to its relatedness with other tumor markers. In the present study, we identified biologically- and clinically-meaningful groups of GC by hierarchical clustering analysis of immunohistochemical protein expression.

METHODS

We selected 28 proteins (p16, p27, p21, cyclin D1, cyclin A, cyclin B1, pRb, p53, c-met, c-erbB-2, vascular endothelial growth factor, transforming growth factor [TGF]-βI, TGF-βII, MutS homolog-2, bcl-2, bax, bak, bcl-x, adenomatous polyposis coli, clathrin, E-cadherin, β-catenin, mucin (MUC)1, MUC2, MUC5AC, MUC6, matrix metalloproteinase [MMP]-2, and MMP-9) to be investigated by immunohistochemistry in 482 GC. The analyses of the data were done using a random forest-clustering method.

RESULTS

Proteins related to cell cycle, growth factor, cell motility, cell adhesion, apoptosis, and matrix remodeling were highly expressed in GC. We identified protein expressions associated with poor survival in diffuse-type GC.

CONCLUSIONS

Based on the expression analysis of 28 proteins, we identified two groups of GC that could not be explained by any clinicopathological variables, and a subgroup of long-surviving diffuse-type GC patients with a distinct molecular profile. These results provide not only a new molecular basis for understanding the biological properties of GC, but also better prediction of survival than the classic pathological grouping.

The prognostic implication of phosphoinositide 3-kinase/Akt pathway in gastric carcinomas

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Background: The phosphatidylinositol 3-kinase (PI3K)/Akt (protein kinase B, PKB) signaling pathway plays a critical role in cell growth and survival. Dysregulation of this pathway has been found in a variety of cancer cells. Recently, constitutively active PI3K/Akt signaling has been firmly established as a major determinant for cell growth and survival in an array of cancers. Blocking the constitutively active PI3K/AKT signaling pathway provides a new strategy for targeted cancer therapy. The purpose of our present study was to investigate the expression of activated mTOR (p-mTOR), PTEN, and pAKT in non-neoplastic gastric tissue and in gastric cancer patients to determine their pattern of expression in gastric tumors and their prognostic significance.

Methods: The expression of p-mTOR, pAKT, and PTEN was detected in specimens of 239 gastric cancers who underwent radical resection (R0) and in 200 non-neoplastic gastric tissues by immunohistochemistry. Slides were scanned and analyzed with an automated cellular imaging system (ACIS III, Dako). The correlation of p-mTOR, pAKT, and PTEN expression to clinicopathologic features and survival of gastric cancer was studied.

Results: Overexpression of pMTOR in the cytoplasmic pattern, nuclear pAKT, and nuclear PTEN was observed in the non-neoplastic tissues when compared with gastric tumor tissues (all, p<0.001). Overexpression of pmTOR, pAKT, and PTEN in gastric tumors was closely correlated with pTNM stage (p<0.001, p=0.008, p=0,036, respectively). Patients with p-AKT positive showed significantly longer disease-free survival (DFS) and overall survival (OS) rates than those with pAKT-negative tumors in univariable analyses. In multivariable analyses, higher expression rates of pMTOR and losses of PTEN were significantly associated with worse overall survival.

Conclusions: Taken together, the observations indicate the PI3K/Akt pathway plays an important role in the gastric carcinogenesis. A new strategy for combined chemotherapy of gastric cancer should be designed to more specifically block PI3K/Akt pathway for selected patients.

Prognostic implications of altered human epidermal growth factor receptors (HERs) in gastric carcinomas: HER2 and HER3 are predictors of poor outcome

PURPOSE

The human epidermal growth factor receptor (HER) family consists of four members: ErbB-1 (HER1), ErbB-2 (HER2), ErbB-3 (HER3), and ErbB-4 (HER4). These receptors activate numerous downstream pathways in response to extracellular ligands, regulating diverse processes that include differentiation, migration, proliferation, and survival. Alterations in these genes play a role in the development and progression of many human cancers. In gastric carcinomas (GCs), expression of HER1 and HER2 is thought to be a prognostic factor and target of novel biologic agents. The effect of HER3 or HER4 expression in GC has not been sufficiently studied. In this study, we explored the gene and protein expression of the HER family in GC to establish new potential prognostic factors.

PATIENTS AND METHODS

Immunohistochemistry and fluorescence in situ hybridization were performed in 221 patients with GC using tissue microarray. Correlation between the expression or amplification of HER genes and the clinicopathologic parameters was statistically analyzed.

RESULTS

Alterations of members of the HER family were significantly associated with the parameters involved in tumor progression, including depth of tumor invasion, involved lymph nodes, and tumor stage. In addition, HER2 amplification and HER3 expression were significantly related to worse survival.

CONCLUSION

These results reveal that all members of the HER family are expressed in GC. Furthermore, expression of HER2 and HER3 is a significant predictor of poor survival in GC. Therefore, the development of HER-targeted agents and agents targeting downstream signaling pathways provides new possibilities in the treatment of GC.

GLUT1 expression in malignant tumors and its use as an immunodiagnostic marker

OBJECTIVE

To analyze glucose transporter 1 expression patterns in malignant tumors of various cell types and evaluate their diagnostic value by immunohistochemistry.

INTRODUCTION

Glucose is the major source of energy for cells, and glucose transporter 1 is the most common glucose transporter in humans. Glucose transporter 1 is aberrantly expressed in several tumor types. Studies have implicated glucose transporter 1 expression as a prognostic and diagnostic marker in tumors, primarily in conjunction with positron emission tomography scan data.

METHODS

Immunohistochemistry for glucose transporter 1 was performed in tissue microarray slides, comprising 1955 samples of malignant neoplasm from different cell types.

RESULTS

Sarcomas, lymphomas, melanomas and hepatoblastomas did not express glucose transporter 1. Forty-seven per cent of prostate adenocarcinomas were positive, as were 29% of thyroid, 10% of gastric and 5% of breast adenocarcinomas. Thirty-six per cent of squamous cell carcinomas of the head and neck were positive, as were 42% of uterine cervix squamous cell carcinomas. Glioblastomas and retinoblastomas showed membranous glucose transporter 1 staining in 18.6% and 9.4% of all cases, respectively. Squamous cell carcinomas displayed membranous expression, whereas adenocarcinomas showed cytoplasmic glucose transporter 1 expression.

CONCLUSION

Glucose transporter 1 showed variable expression in various tumor types. Its absence in sarcomas, melanomas, hepatoblastomas and lymphomas suggests that other glucose transporters mediate the glycolytic pathway in these tumors. The data suggest that glucose transporter 1 is a valuable immunohistochemical marker that can be used to identify patients for evaluation by positron emission tomography scan. The function of cytoplasmic glucose transporter 1 in adenocarcinomas must be further examined.

Abstract A3: The human epidermal growth factor receptors in gastric carcinomas: A study using fluorescence in situ hybridization and immunohistochemistry

The human epidermal growth factor receptors (EGFR) family consists of four members: ErbB-1 (HER1), ErbB-2 (HER2), ErbB-3 (HER3) and ErbB-4 (HER4). These receptors activate numerous downstream pathways in response of extracellular ligands, regulating diverse processes including differentiation, migration, proliferation, and survival. Alterations in EGFR family members play a role in the development and progression of many human cancers. In gastric carcinomas (GC), HER1 and HER2 overexpressions are thought to be prognostic factors and targets of novel biological agents. The effect of HER3 or HER4 expression in GC has not been sufficiently studied. HER3 expression is observed frequently in advanced GC with poor prognosis and HER4 gene expression seems to be higher in GC tissue in comparison with adjacent gastric mucosa. In this study, we explored gene and protein expression of the EGFR family in GC in order to establish new potentially prognostic factors. Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) were carried out in 221 GC using tissue microarray. IHC positivity for EGFR was defined by score 2+ or 3+ according with intensity and frequency of membranous staining. In addition, the intensity of the cytoplasm staining was also determined for HER3 and HER4 overexpression. HER1, HER2, HER3, and HER4 overexpression was found in 3/197 (1.5%), 24/207 (12%), 121/193 (64%) and 41/183 (22%) cases respectively. FISH assay was performed according to the protocol previous described. In each case, 100 tumor nuclei were evaluated. Cases showing a gene/CEN fluorescence ratio ≥ 2 were considered positive for gene amplification. FISH detected HER1 and HER2 amplification in 1.3% and 8% of the cases. Amplifications for HER3 and HER4 were not observed. Overall, alterations of the 4 members of EGFR were significantly associated with parameters involved with tumor progression, including the depth of tumor invasion, involved lymph nodes, and tumor stage. We herein showed a strong correlation between HER2, HER3 and HER4 overexpression and low-grade tumors, corresponding to the intestinal type GC according to Lauren's classification. In addition, HER2 amplification was significantly related with worse survival. These results reveal that members of EGFR family are activated in GC. The exact molecular mechanisms involved in the HER3 or HER4 alterations in gastric cancer, especially in the intestinal type, remain unclear since amplifications of these genes were not found. Gaining further understanding into the oncogenic mechanism of EGFR family may not only help in the development of targeted therapy in gastric patients but might accelerate the acceptance of a novel taxonomy of cancer which is based on the genomic perturbations in cancer genes and cancer gene families and their response to targeted agents.

Citation Information: Clin Cancer Res 2010;16(14 Suppl):A3.

Evaluation of cell cycle protein expression in gastric cancer: cyclin B1 expression and its prognostic implication

The cell cycle progression is regulated by interactions of specific cyclin-dependent kinases at the G1-S and G2-M checkpoints. In addition, the cell cycle dysregulation plays a major role in carcinogenesis of human cancers. To investigate the role of cell cycle regulators in the pathogenesis and progression of human gastric cancer, the expression of cyclin D1, A, B1, p16(INK4a), p21(CPI1), p27(KIP1), p53, and pRb was investigated in 482 gastric carcinomas using immunohistochemistry in terms of histologic type, tumor invasion, size, location, and metastatic behavior. The cyclin D1, A, and B1 expression (>10%) was observed in 49%, 69%, and 49% of the cases, respectively. Negative cases for p16(INK4a), p21(CPI1), and p27(KIP1) were detected in 90%, 86%, and 50.5%. There were 30% and 68% of the gastric tumors positive for p53 and pRb, respectively. Diffuse carcinomas frequently were positive for cyclin B1 and pRb, and negative for p21. A relationship between p53 expression and intestinal type carcinomas was found. In addition, the expression of cyclin B1 was associated with regional lymph node metastasis and poor prognosis. No relationship was noticed between any other cell cycle proteins expression and age, sex, tumor size, tumor location, and lymph node involvement. These findings have shown alterations in several cell cycle regulators, and it was suggested that cyclin B1 expression is closely associated with poor behavior in gastric cancer.

Cadherin-catenin adhesion system and mucin expression: a comparison between young and older patients with gastric carcinoma

BACKGROUND

Young patients are thought to develop gastric carcinomas with a molecular genetic profile that is distinct from that of gastric carcinomas occurring at a later age. The aim of this study was to compare the clinicopathological features and expression patterns of the markers E-cadherin and beta-catenin, and mucins (MUC1, MUC2, MUC5AC, and MUC6) in young and older patients.

METHODS

The clinicopathological features and overall survival data of 62 young patients (age <or=40 years) with gastric cancer were retrospectively reviewed from hospital records and compared with the data for 453 older patients (age >40 years). A tissue microarray method and immunohistochemistry were used in order to analyze marker expression in paraffin-embedded tissue blocks obtained from both groups.

RESULTS

The young group presented a higher percentage of diffuse-type tumors in comparison to the older group (P<0.01). The rates of positivity for E-cadherin and beta-catenin membranous expression patterns and mucin (MUC2, MUC5AC and MUC6) positivity were higher in the young group (P<0.01). Although young patients showed a lower frequency of alterations in marker expression and had significantly better survival rates than the older patients, neither age nor the marker expression pattern were found to be independent prognostic factors of survival. Only stage, tumor size, and tumor location persisted as prognostic factors for patients with gastric cancer.

CONCLUSION

Biological markers of cellular adhesion and gastric differentiation were differently expressed in young and older patients. Our findings support the hypothesis that young patients develop carcinomas with a different genetic pathway compared to the pathway of tumors occurring at a later age, and we suggest further investigations to assess the prognostic relevance of the markers to specific subgroups.

Evaluation of NF2 gene deletion in sporadic schwannomas, meningiomas, and ependymomas by chromogenic in situ hybridization

Fluorescence in situ hybridization, loss of heterozygosity testing, and comparative genomic hybridization have been used to detect NF2 gene alterations in both sporadic and neurofibromatosis type 2 (NF2)-associated central nervous system tumors. In this study, we performed chromogenic in situ hybridization (CISH) and immunohistochemistry to evaluate for NF2 gene deletion in a group of sporadic meningiomas, schwannomas, and ependymomas. Twenty-two sporadic tumors, including 9 ependymomas, 10 meningiomas, and 3 schwannomas, were studied. CISH and immunohistochemistry were performed using the NF2 gene deletion probe and NF2 polyclonal antibody. Deletion of the NF2 gene was identified in 11 (50%) tumors, including 60% (6/10) of meningiomas, 33% (3/9) of ependymomas, and 67% (2/3) of schwannomas. The remaining 11 (50%) cases were diploid. Overall, immunoexpression of NF2 protein was observed in 50% (11/22) tumors, and concordance between CISH and immunohistochemistry was observed in 73% of cases. Our results support previous observations that schwannomas and meningiomas, and to a lesser degree, ependymomas, express a high incidence of NF2 gene deletion, which supports the hypothesis that NF2 gene plays an important role in their tumorigenesis. In addition, we have validated CISH as an efficient, economic, and reliable method for routinely assessing NF2 gene deletion in these tumors.

Differential expression of apoptosis related proteins and nitric oxide synthases in Epstein Barr associated gastric carcinomas

AIM: To determine the incidence of Epstein Barr virus associated gastric carcinoma (GC) in Brazil and compare the expressions of apoptosis related proteins and nitric oxide synthases between EBV positive and negative gastric carcinoma.

METHODS: In situ hybridization of EBV-encoded small RNA-1 (EBER-1) and PCR was performed to identify the presence of EBV in GCs. Immunohistochemistry was used to identify expressions of bcl-2, bcl-xl, bak, bax, p53, NOS-1, NOS-2, and NOS-3 proteins in 25 EBV positive GCs and in 103 EBV negative GCS.

RESULTS: 12% of the cases of GC (25/208) showed EBER-1 and EBNA-1 expression. The cases were preferentially of diffuse type with intense lymphoid infiltrate in the stroma. EBV associated GCs showed higher expression of bcl-2 protein and lower expression of bak protein than in EBV negative GCs. Indeed, expressions of NOS-1 and NOS-3 were frequently observed in EBV associated GCs.

CONCLUSION: Our data suggest that EBV infection may protect tumor cells from apoptosis, giving them the capacity for permanent cell cycling and proliferation. In addition, EBV positive GCs show high expression of constitutive NOS that could influence tumor progression and aggressiveness.

Antigen retrieval methods and estrogen receptor immunoexpression using 1D5 antibody: a comparative study

Long-term formalin tissue fixation results in antigen masking, probably through aldehydic linkage between proteins and fixative molecules. Immunohistochemistry results depend on the type of the detection procedure and the type of antibody used for the reaction. Considering the difficulty in working with estrogen receptor (ER) antibodies and the lack of standardization of the antigen retrieval methods, we quantified the immunoexpression of ER using the 1D5 antibody and a standard streptavidin-biotin detection procedure retrieving with microwave oven, steamer, pressure cooker, and water bath in a set of SBR grade 2 invasive breast carcinomas. Pressure-cooking provided the best results. No significant differences were observed in using the other methods. Pressure-cooking should be recommended as the method of choice for standardization of the ER immunohistochemical reaction.

Desmoplastic small round cell tumour: Cytological and immunocytochemical features

Background

Desmoplastic small round cell tumor (DSRCT) is a rare and highly aggressive neoplasm. The cytological diagnosis of these tumors can be difficult because they show morphological features quite similar to other small round blue cells tumors. We described four cases of DSRCT with cytological sampling: one obtained by fine needle aspiration biopsy (FNAB) and three from serous effusions. The corresponding immunocytochemical panel was also reviewed.

Methods

Papanicolaou stained samples from FNAB and effusions were morphologically described. Immunoreaction with WT1 antibody was performed in all cytological samples. An immunohistochemical panel including the following antibodies was performed in the corresponding biopsies: 34BE12, AE1/AE3, Chromogranin A, CK20, CK7, CK8, Desmin, EMA, NSE, Vimentin and WT1.

Results

The smears showed high cellularity with minor size alteration. Nuclei were round to oval, some of them with inconspicuous nucleoli. Tumor cells are clustered, showing rosette-like feature. Tumor cells in effusions and FNA were positive to WT1 in 3 of 4 cytology specimens (2 out 3 effusions and one FNA). Immunohistochemical reactions for vimentin, NSE, AE1/AE3 and WT1 were positive in all cases in tissue sections.

Conclusion

The use of an adjunct immunocytochemical panel coupled with the cytomorphological characteristics allows the diagnosis of DSRCT in cytological specimens.

Molecular classifiers for gastric cancer and nonmalignant diseases of the gastric mucosa

High incidence of gastric cancer-related death is mainly due to diagnosis at an advanced stage in addition to the lack of adequate neoadjuvant therapy. Hence, new tools aimed at early diagnosis would have a positive impact in the outcome of the disease. Using cDNA arrays having 376 genes either identified previously as altered in gastric tumors or known to be altered in human cancer, we determined expression signature of 99 tissue fragments representing normal gastric mucosa, gastritis, intestinal metaplasia, and adenocarcinomas. We first validated the array by identifying molecular markers that are associated with intestinal metaplasia, considered as a transition stage of gastric adenocarcinomas of the intestinal type as well as markers that are associated with diffuse type of gastric adenocarcinomas. Next, we applied Fisher's linear discriminant analysis in an exhaustive search of trios of genes that could be used to build classifiers for class distinction. Many classifiers could distinguish between normal and tumor samples, whereas, for the distinction of gastritis from tumor and for metaplasia from tumor, fewer classifiers were identified. Statistical validations showed that trios that discriminate between normal and tumor samples are powerful classifiers to distinguish between tumor and nontumor samples. More relevant, it was possible to identify samples of intestinal metaplasia that have expression signature resembling that of an adenocarcinoma and can now be used for follow-up of patients to determine their potential as a prognostic test for malignant transformation.