Mário Seixas

The Clinicopathological Features of Gastric Carcinomas with Microsatellite Instability May Be Mediated by Mutations of Different “Target Genes”: A Study of the TGFβ RII, IGFII R, and BAX Genes

Gastric carcinomas with DNA replication errors (RER phenotype) display a particular clinicopathologic profile and carry a putative favorable prognosis. The RER phenotype has been identified as microsatellite instability in noncoding regions, as well as in repeat sequences within exons of several “target genes”: TGFβ RII, IGFII R, and BAX. In an attempt to find out whether the RER status is a significant prognostic factor in gastric carcinoma in a multivariate analysis and whether the clinicopathological features of the RER+ tumors are associated with mutations in the “target genes,” we evaluated a series of 152 cases of sporadic gastric carcinoma. Five or six microsatellite loci and/or BAT 26, a poly(A) tract, were analyzed in each case using polymerase chain reaction and electrophoresis. Thirty-five cases (23.0%) were RER+. The RER phenotype was closely associated with a low pTNM stage and carried a significantly better prognosis. The repeat sequences of the target genes were screened for mutations in 28 RER+ and 13 RER− tumors. Mutations in TGFβ RII occurred in 67.9% of the RER+ tumors and were significantly associated with the glandular histotype. IGFII R and BAX mutations occurred, respectively, in 25.0% and 32.1% of the cases; there was a trend toward an association between mutations in these genes and decreased nodal metastization and wall invasiveness, respectively. We conclude that the RER status is a significant prognostic indicator in gastric carcinoma and that such prognostic influence may be mediated by mutations in TGFβ RII, IGFII R, and BAX genes.

EXPRESSION OF FULLY AND UNDER-GLYCOSYLATED FORMS OF MUC1 MUCIN IN GASTRIC CARCINOMA

The membrane‐bound MUC1 mucin is expressed in normal mucosas and the aberrant expression of its under‐glycosylated forms has been reported in carcinomas from different sites. Several studies have provided conflicting evidence regarding the relationship between MUC1 expression and outcome in cancer patients. In this study, we investigated the immunohistochemical expression of MUC1 epitopes, using 2 monoclonal antibodies (MAbs): HMFG1, which reacts with the fully glycosylated MUC1, was studied in 73 gastric carcinomas; and SM3, which recognises an under‐glycosylated form of MUC1, was studied in 180 cases. HMFG1 stained the antrum foveolar cells and the body glands of normal gastric mucosa, whereas SM3 reactivity was restricted to the perinuclear region of some foveolar cells. Type I intestinal metaplasia exhibited down‐regulation of MUC1 expression using both MAbs. Every gastric carcinoma was stained with HMFG1 and 80% with SM3. High levels of expression of HMFG1 were associated with lymphatic invasion, nodal metastatization, and advanced pTNM staging. The expression of SM3 was associated with the histologic (solid) type of carcinoma, expanding growth pattern, wall penetration, lymphatic invasion and age of the patients. Despite a trend for a poor outcome in patients with tumours (over)expressing MUC1 mucin, the survival of the patients evaluated by univariate and multivariate analysis was not significantly associated with the levels of expression of HMFG1 or with the expression of the SM3 epitope. We conclude that (a) MUC1 expression, namely of the SM3 cancer‐associated epitope, is significantly associated with several aspects of gastric cancer development and progression; and (b) MUC1 expression should not be used as a prognostic marker in patients with gastric carcinoma. Int. J. Cancer (Pred. Oncol.) 79:402–410, 1998.

New elements for an updated classification of the carcinomas of the stomach.

Based upon the results of a thorough study of 213 patients submitted to potentially curative resection we propose the following histologic classification of gastric carcinoma: isolated-cell carcinoma (6.6%), glandular carcinoma (41.8%), solid carcinoma (13.1%) and mixed carcinoma (38.5%). Half of the mixed carcinomas displayed a predominant isolated-cell pattern, whereas in the other half the isolated-cells were a minor component (the predominant component being either glandular, solid, or both). The survival of patients with mixed carcinomas is significantly worse than those of patients with other histologic types of gastric carcinoma regardless of the site of tumors and the inclusion, or not, in the series, of post-operative deaths. The proposed classification keeps its independent prognostic significance in a multifactorial analysis, appearing as the second most important prognostic factor in patients with gastric carcinomas, after the TNM staging and before venous invasion.

MUC1 gene polymorphism and gastric cancer— an epidemiological study

Gastric carcinoma is a major cause of cancer death worldwide and, like most human cancers, probably develops after environmental insults acting on normal individuals and/or individuals with increased genetic susceptibility. Mucins are attractive molecules to study the relationship between genetics and environment because they play an important role in the protection of gastric mucosa against environmental insults and exhibit a highly polymorphic genetic variation. We performed a case-control study using Southern blot analysis to evaluate the MUC1 gene polymorphism in a series of blood donors (n=324) and in patients with gastric carcinoma (n=159). We found that the distribution of MUC1 alleles is significantly different in the two populations and that small MUC1 alleles and small MUC1 genotypes are significantly more frequent in patients with gastric carcinoma than in controls. Individuals with small MUC1 genotypes are at increased risk for gastric carcinoma development.

Dimeric sialyl-Lex expression in gastric carcinoma correlates with venous invasion and poor outcome

BACKGROUND & AIMS High expression of sialyl-Le(x) in tumors of different organs correlates with hematogenous metastasis and adverse outcome. Dimeric sialyl-Le(x) expression in gastric carcinoma was evaluated, and its prognostic significance within this setting was determined. METHODS Dimeric sialyl-Le(x) immunohistochemical expression in 97 gastric carcinomas was analyzed using the FH6 monoclonal antibody. Scoring was based on the percentage of immunoreactive cells: negative, low expression (< or = 25%), and high expression (> 25%). RESULTS Immunoreactivity was observed in 45 cases (46.4%), encompassing 27 and 18 cases with low and high expression, respectively. Significant relationships were found between dimeric sialyl-Le(x) expression and venous invasion (P = 0.0025) and histological classification (P = 0.05). No correlation was observed with other clinicopathologic features. Patients with tumors showing high expression of dimeric sialyl-Le(x) had a significantly shorter survival time than those with low or no expression (P = 0.03). By multivariate analysis, pathological TNM (pTNM) staging and venous invasion emerged as independent prognostic factors in the whole series. Within the group of patients with tumors in pTNM stages II and III, dimeric sialyl-Le(x) was the only independent prognostic factor. CONCLUSIONS High expression of dimeric sialyl-Le(x) correlates with venous invasion and poor outcome in gastric carcinoma.

c-erb B-2 Expression Is Associated with Tumor Location and Venous Invasion and Influences Survival of Patients with Gastric Carcinoma:

The HER-2/neu gene or c-erb B-2, localized on chromosome 17q, belongs to a family of tyrosine kinase receptors and shares extensive homology with the epidermal growth factor receptor. c-erb B-2 gene amplification and protein overexpression have been reported in several human cancers. The prognostic value of this genetic alteration in gastric carcinoma is far from being established. In the present study, formalin-fixed, paraffin-embedded gastric carcinoma tissues from 157 patients were evaluated for c-erb B-2 overexpression, by immunohistochemistry using a polyclonal antibody. c-erb B-2 expression was evaluated according to clinical and pathological parameters, and to the survival of the patients. Our results show that: (1) c-erb B-2 was overexpressed in 15.3% of gastric carcinoma cases; (2) c-erb B-2 overexpression was significantly more frequent in cardia (23.8%) and fundus/body (25.0%) carcinomas than in antrum (7.2%) carcinomas; (3) c-erb B-2 overexpression was significantly associated with venous invasion; (4) c-erb B-2 is a prognostic factor for gastric carcinoma.

Ki67 LABELLING INDEX IN GASTRIC CARCINOMAS. AN IMMUNOHISTOCHEMICAL STUDY USING DOUBLE STAINING FOR THE EVALUATION OF THE PROLIFERATIVE ACTIVITY OF DIFFUSE‐TYPE CARCINOMAS

The aim of the present study was to clarify the conflicting recorded data on the proliferative features of gastric carcinoma. The Ki67 labelling index (Ki67 LI) was evaluated using MIB‐1 in 43 carcinomas (24 diffuse and 19 intestinal). In 18 cases, differential counts were performed in superficial and deep layers. In ten diffuse carcinomas with a prominent desmoplastic response, Ki67 LI was evaluated in sections double‐stained with MIB‐1 and CAM5.2. Flow cytometry was performed in 26 cases. Ki67 LI of diffuse carcinomas (36·3±19·0) was not significantly different from that of intestinal carcinomas (28·2±18·5). Ki67 LI was significantly higher (P=0·006) in superficial than in deep areas (41·9±22·7 and 29·7±19·7, respectively) regardless of histological tumour type. No significant relationship was observed between Ki67 LI and wall invasion, lymph node metastasis, vascular invasion or ploidy. The following conclusions were drawn: double immunostaining techniques are apparently the best way to overcome the underestimation of cell proliferation in diffuse gastric carcinomas with a prominent desmoplastic response; the diffuse and intestinal types of gastric carcinoma have proliferation rates within the same range, even when the comparison is restricted to diploid tumours; and, finally, the major pool of proliferating cells resides in the superficial areas of gastric carcinomas, regardless of the histotype, which should be taken into consideration when overall counts are performed, using either immunohistochemical markers in tissue sections or suspensions of nuclei in flow cytometry.

Clinicopathologic profiles and prognosis of gastric carcinomas from the cardia, fundus/body and antrum.

Background/Aims: The putative influence of tumor location on the biologic behavior of gastric carcinomas remains controversial. The aim of this study was to investigate if carcinomas arising in the three types of gastric mucosa (cardia, fundus/body and antrum) have different clinical and pathologic profiles and carry a different prognosis. Methods: Three hundred and two patients with cardia or gastric carcinoma resected between 1984 and 1996 were retrospectively studied. Cases were divided in three groups according to tumor location: cardia (n = 80); fundus/body (n = 60); antrum (n = 162). The three groups were crosstabulated with clinic and pathologic parameters, such as age, sex, macroscopy, histology, desmoplasia, tumor size, depth of tumor wall penetration, nodal status, venous invasion and stage. Survival rates were calculated for the three locations according to the aforementioned parameters. Univariate survival analysis and Cox regression were performed for each location. Results: Cases from the cardia and fundus/body were similar and distinct from antrum cases according to macroscopy, tumor size, depth of wall penetration, venous invasion, nodal status and stage. Cases from fundus/body were similar to antrum cases and distinct from cardia cases according to gender and Laurén’s classification. An overall difference in survival between the three locations was observed (p = 0.006). Cumulative survival was better for patients with carcinomas in the antrum than in the cardia (p = 0.04) and in the fundus/body (p = 0.003); no significant differences were observed in survival between cardia and fundus/body carcinoma cases. Cox regression identified stage and venous invasion as prognostic factors for patients with carcinomas in the three locations. In the group of cardia tumors, older patients had a worse outcome and in the group of fundus/body carcinomas, large tumors were associated with a poorer survival. Conclusions: Our results show that cardia carcinoma and antrum carcinoma are distinct gastric carcinoma entities whereas fundus/body carcinoma shares some characteristics from both entities.

Clinicopathological significance and survival influence of p53 protein expression in gastric carcinoma

Aims:  Mutations in the gene coding for p53 protein are among the most frequent genetic alterations observed in human cancers. The relevance and biological significance of p53 expression in gastric carcinoma are far from being fully established. The aim of our study was to evaluate the influence of p53 detected by immunohistochemistry in the clinicopathological behaviour of a series of gastric carcinoma cases.

Signet Ring Cell Carcinoma of the Stomach: A Morphometric, Ultrastructural, and DNA Cytometric Study

The present study was undertaken to determine whether or not signet ring cell (diffuse, isolated cell) gastric carcinomas display a specific profile at the ultrastructural, morphometric, and DNA cytometric levels. Thirty-two cases of gastric carcinoma and 8 cases of peptic ulcer (control group) were studied with electron microscopy, morphometry, flow cytometry, and image cytometry. Despite the ultrastructural cellular heterogeneity of signet ring cell carcinomas, the neoplastic cells display fairly constant morphometric features: The cellular and nuclear volumes are significantly smaller than those of the other types of gastric carcinomas and closely resemble those of normal foveolar cells. The relatively small size of signet ring cell carcinoma nuclei fits with the high percentage of the cases of this type of gastric carcinoma that are either diploid or nearly diploid. There is a relationship between the infiltrative pattern of growth of gastric carcinoma (regardless of histologic subtype and ultrastructural cell differentiation) and the small size of neoplastic cells and their nuclei.