[P53 tumor suppressor gene in digestive neoplasms]

Malignant diseases of the digestive tract cause more than 50% of deaths due to cancer in Chile. There is a high incidence of gastric and gallbladder cancer and an increasing frequency of colorectal cancer. P53 tumor suppressor gene has a great importance in carcinogenesis and its alterations are specially important in digestive tract tumors such as colorectal cancer. There is contradictory evidence about the frequency of p53 gene or protein alterations or their biological significance. There is little information about p53 in Chile and it is mostly limited to immunohistochemical studies. This revision analyzes the frequency of p53 alterations in digestive tract tumors in Chile, using immunohistochemical and molecular biology methods. A special emphasis is given to the prognostic importance of this gene.

[p53 gene mutation in cancer of the colon and rectum]

BACKGROUND

Genetic events associated to colorectal carcinoma are well characterized, but there is scanty information about this issue in Chilean subjects.

AIM

To determine the frequency and distribution of exons 5, 6, 7, 8 and 9 mutations and the immunohistochemical expression of p53 gene in biopsy samples of colorectal carcinoma.

MATERIAL AND METHODS

p53 gene exons 5, 6, 7, 8 and 9 were directly sequenced in 42 biopsy samples of colorectal carcinoma. Immunohistochemical expression of p53 was determined in 35 samples.

RESULTS

Thirty one discrete mutations (12 transitions, 11 transversions and 8 insertions) were observed in 21 samples (60%). Nine samples had mutations in exon 5, twelve samples had mutations in exon 6, seven samples had mutations in exon 7 and three samples had mutations in exons 8 and 9. Immunohistochemical expression of p53 protein was observed in 18 of 35 cases. There was a high correlation between the genetic alteration and immunohistochemistry, when p53 was expressed in more the 20% of cells. The positive and negative predictive values of p53 expression were 87 and 80% respectively. There was a non significant lower mortality among patients with mutations in their biopsies.

CONCLUSIONS

These results confirm the involvement of p53 gene mutations in colonic carcinogenesis. Immunohistochemical methods for the detection of p53 protein have a high predictive value.

[Helicobacter pylori and chronic gastritis: relationship between infection and inflammatory activity in a high risk population for gastric cancer]

BACKGROUND

Helicobacter pylori has been involved in gastric epithelial cell damage and gastric gland loss or atrophy.

AIMS

To evaluate role of Helicobacter pylori infection in acute and chronic changes of chronic gastritis in a high gastric cancer-risk population.

MATERIAL AND METHODS

200 patients with chronic gastritis were selected from pathological files of Temuco Hospital. A complete histopathological protocol was fulfilled considering the presence of infection by Helicobacter pylori-like-organism (HLO), acute and chronic inflammatory infiltrate, epithelial cell damage and epithelial cell regeneration.

RESULTS

82% of patients showed infection by HLO. Moreover, this infection reached a frequency of 92.7% in gastric ulcer patients and 94.4% in duodenal ulcer patients. A statistically significant positive correlation was found between HLO infection and polymorphonuclear infiltrate, lymphocytic infiltrate, mucus depletion and epithelial regenerative activity. There was not a statistical correlation between HLO infection and atrophy. Finally, 90% of patients with multifocal atrophic gastritis and 100% of patients with diffuse antral gastritis had HLO infection.

CONCLUSIONS

HLO gastric infection frequently caused acute inflammatory changes in gastric mucosa with chronic gastritis. Sometimes these changes were severe, with marked polymorphonuclear migration throughout epithelium and severe epithelial cell damage. Recovery of these changes could be considered as a goal in Helicobacter pylori eradication therapy decision.

Double immunostaining for p53 and molecular chaperone hsp72/73 in gastric carcinoma

AIMS

To examine the relation between the expression of p53 protein and the chaperone heat shock protein (hsp)72/73 in a population at high risk for gastric carcinoma, using single and double immunohistochemistry, and to compare the expression of these two proteins with clinicopathological features.

METHODS

Monoclonal antibodies were used to investigate the expression of p53 protein and hsp72/73 in 46 human gastric carcinomas. A double immunohistochemical technique was used in cases that showed p53/hsp72/73 coexpression.

RESULTS

p53 immunoreactivity was present in 11 tumours (24%), and hsp72/73 immunostaining was observed in 22 cases (48%). p53 expression was observed as nuclear staining in tumoral cells. hsp72/73 expression was demonstrated mainly as cytoplasmic staining, but six tumours also showed focal weak nuclear staining. Seven cases showed p53 and hsp72/73 coexpression with immunoreactivity for both proteins in the same neoplastic cells, three of them with focal areas of nuclear coexpression. p53 expression was seen more frequently in cases that showed a high intensity (+ + +) of hsp72/73 staining. No significant association was observed between the expression of the two proteins and clinicopathological features.

CONCLUSIONS

More than half of our cases may have some impairment in p53 protein growth suppressive function, as a result of p53 gene alterations or complex formation. The positive correlation between p53 expression and intensity of hsp72/73 supports the postulate of a p53 regulating function for the chaperone hsp72/73. A high intensity of hsp72/73 immunohistochemical staining could be used as an indirect marker of p53 gene abnormalities.

Curative resection in potentially resectable tumours of the gallbladder

OBJECTIVE

To study the value of surgical treatment in patients with potentially resectable gallbladder cancer.

DESIGN

Prospective non-randomised study.

SETTING

University hospital, Chile.

SUBJECTS

109 Patients with gallbladder cancers, most of which were detected in the cholecystectomy specimen.

INTERVENTIONS

53 Patients underwent reoperation with the aim of doing a lymphadenectomy and resecting the gallbladder bed.

MAIN OUTCOME MEASURES

Morbidity and short and long term mortality

RESULTS

Residual tumour after cholecystectomy was mainly observed in patients with serosal and adipose tissue infiltration. Lymph nodes and liver invasion were associated with recurrence. Survival analysis was focused on the group with subserosal infiltration because it is the largest subgroup in this study and prognosis is intermediate. Patients who underwent curative resection had a significantly better survival than those treated by simple cholecystectomy (p = 0.005).

CONCLUSIONS

Extended cholecystectomy improved the prognosis of patients whose cancers were restricted to the subserosal layer. Additional treatments are necessary to improve the results obtained with operation alone.

[Immunohistochemical expression of p53 oncoprotein in large bowel adenomas and carcinomas]

BACKGROUND

Colorectal carcinoma is the sixth cause of death in Chile. Half of malignant tumors in humans have genetic alterations in protoncogenes, tumor suppressing genes or both. One of the most frequent alterations is that involving p53 tumor suppressor gene.

AIM

To study, using immunohistochemical methods, alterations in p53 gene expression in colorectal carcinomas and adenomas.

MATERIAL AND METHODS

A random sample of 28 large bowel adenomas and 44 carcinomas was studied. Determination of p53 protein was made with an immunohistochemical method using monoclonal antibodies. Patients were followed for a mean of 36 months (range 1 to 100 months).

RESULTS

p53 immunostaining was obtained in one adenoma (3.5%) and in 18 carcinomas (41%, p = 0.01). There were no differences in survival during follow up, between cancer patients that expressed or did not express p53 protein.

CONCLUSIONS

About half of colorectal tumors have immunohistochemical expression of p53 protein, as published abroad. We did not find a prognostic value for this protein in our sample.

[Expression of p29, estrogen receptor related protein in primary breast carcinoma. Methodological, anatomoclinical, and DNA content analysis]

The aim of this work was to assess the immunohistochemical detection of a estrogen receptor related protein (p29) in 48 histological samples of primary mammary carcinoma and its relationship to clinical, morphological and ADN content parameters. p29 protein was positive in 62.5% of samples. Over 50% of samples had a moderate or intense immunohistochemical staining (staining index over 16) and 77% has a heterogeneous expression of p29 protein. Seventy six percent of p29 positive and 53% of p29 negative tumors had a proliferation fraction over 10% (determined by the S fraction with flux cytometry). No relationship between p29 expression and the analyzed anatomoclinical variables was found. These results highlight this immunohistochemical method as an alternative to more complex and difficult biochemical techniques. On the other hand, the good results obtained in formalin fixed tissues allow retrospective studies in mammary carcinoma samples.

[Proliferating cell nuclear antigen (PCNA) in patients with malabsorption syndrome: comparative study with morphometric parameters]

The study of small bowel mucosa is routine in the study of patients with malabsorption. We report 16 children aged from 8 months to 6 years old (2 with giardiasis, 8 with primary malnutrition and 5 with celiac disease) in whom a morphometric and PCNA immunostaining was performed in the small intestinal biopsy. Positivity for PCNA was found in the lower portion of the crypts reaching 156 microns of heigh in patients with giardiasis, 103 microns in primary malnutrition and 182 microns in celiac disease (p < 0.01 compared to primary malnutrition). A negative and significant correlation was found between the degree of architectural disorder (expressed the mucosal index) and the proliferative portion of the crypts (expressed as the percentage of PCNA(+) crypts. We propose these methods as complements to the small bowel mucosa histopathological study in the diagnosis of celiac disease, to assess the degree of architectural disorder and the proliferative activity.

[Breast cancer and flow cytometry: comparative study of DNA ploidy pattern with clinicopathological parameters]

There is evidence that DNA quantization and histopathological classification of breast cancer may be useful for its therapeutic management. DNA flow cytometry, clinical and anatomopathological features of 60 paraffin embedded primary breast cancer tissue samples were studied. The aneuploidy percentage was 67%. There was a correlation between DNA index and degree of cellular pleomorphism, degree of differentiation and the fraction of cells in S phase. Likewise a correlation was found between the degree of cellular pleomorphism and the mitotic index. DNA cytophotometry was useful to solve cases of difficult diagnosis with flow cytometry ("near" diploid and tetraploid tumors). No correlation was found between aneuploidy, percentage of cells in phase S, degree of cellular atypia and mitotic degree with clinical stage, degree of lymph node involvement, tumoral size or age. It is suggested that these variables may have an independent behavior.

[Mutagen extraction from bile of patients with inflammatory biliary pathology: Ames test using blue rayon]

Gallbladder carcinoma is frequent in Chile. The aim of this study was to report the mutagenicity of whole human bile, using the Ames/Salmonella microsome assay with Salmonella typhimurium TA98. The bile of 19 patients, aged 23 to 64 years old, subjected to cholecystectomy was examined, and mutagen activity was found in 13 (72%). Mutagens were extracted using blue rayon and three dilutions for the eluted material from blue rayon were used (50, 100 and 200 ul). The best result was obtained using 200 ul. In some cases, the amount of revertive colonies was very high (over 5 times the control value). We propose that the bile from these patients possibly contains mutagenic substances with frame shift mutagenic activity and that these substances may be related to gallbladder carcinoma. Our results have addressed the importance of bile studies to elucidate the pathogenesis of gallbladder carcinoma.

[Cervix uteri cancer: determination of DNA content by means of cytophotometry]

ADN content was measured using cytofluorometry in 31 infiltrative uterine cervical carcinomas, using 22 routine cytologic cervical spreads (18 from archives) and 9 cellular spreads obtained from the fresh surgical specimen. Results were correlated to the clinical staging and morphological parameters of the tumor. Eight samples (25.8%) were diploid and 23 (74.2%) aneuploid. Women with diploid tumors were not significantly older. No correlation was found between ADN content and clinical staging, degree of histological differentiation, degree of cervical wall infiltration or the presence of vascular tumor permeations. All the cytological spreads were adequate for the cytofluorometric study. It is concluded that a high percentage of cervical carcinomas are aneuploid and that the present technique can be applied successfully to cytological samples.

[Characteristics of gastric cancer in the IX region of Chile]

The results of a prospective protocol for the management of patients with gastric cancer applied from May 1988 to June 1991 are reported. 123 patients were operated on and a resection performed in 55%. Only 14 patients had incipient tumor and 44 had "curative" surgery. There was a preponderance of non differentiated tumors located high in the stomach. Endoscopy and biopsy were performed in cases with positive diagnosis in 91 and 93%, respectively. The overall actuarial survival rate was 37% at 38 months, rising to 50% for patients undergoing resection and to 82% in patients with "curative" resection.

[Inapparent cancer of the gallbladder]

Gallbladder cancer is the most common cancer in the Chilean female population. A prospective histological mapping of cholecystectomy pieces allowed the detection of 37 tumors not evident to the surgeon. Tumoral invasion engaged the mucous membrane in 7, the muscular layer in 8, the subserous layer in 12, the serous membrane in 5 and the surrounding adipose tissue of the gallbladder in 5 cases. 18 pts were reoperated on for resective oncological surgery. In 5 of these cases the ganglia, and in 6 the hepatic tissue behind the gallbladder were involved. Actuarial survival at 38 months was 48% (10 pts have died by the time of this publication). The prognosis of the disease was directly related to histological differentiation and to the degree of tumoral invasion. Gallbladder cancer has a poor prognosis even if the surgeon has no suspicion of the disease and a simple cholecystectomy is by no means a healing therapy.