La derivación protocolizada a endoscopía asociada a la detección de Helicobacter pylori mediante antígeno en deposiciones disminuye lista de espera para endoscopía y optimiza la detección de lesiones pre-malignas y cáncer gástrico incipiente / Protocolized referral to endoscopy and Helicobacter pylori detected in stools aimed to decrease endoscopy waiting lists

Background Chile has one of the highest mortality rates by gastric cancer (GC) worldwide. Primary prevention of GC and detection of pre-neoplastic and early neoplastic lesions should be a national priority. Aim To assess the impact of the protocolization of endoscopy referral and the use of H. pylori stool antigen test (HPSA) in the management of dyspepsia to decrease the waiting list for endoscopy and increase the detection of gastric pre-neoplastic and early neoplastic lesions. Material and Methods We included all patients referred to the Endoscopy Unit of a regional hospital, from January 2015 to December 2017. We also included patients with known pre-neoplastic lesions and all those with first degree relatives with GC. We implemented protocols for referral of patients with dyspepsia considering the use of HPSA test, prioritizing to endoscopy those with a higher risk of GC. Results A total of 4,641 endoscopies and 2,631 HPSA tests were carried out. After the adoption of these protocols, we observed a 52% decrease in the waiting time for endoscopy. The GC detection rate in this period was 1.8 to 3.1 cases per 100 endoscopies. After the adoption of the protocols, we observed a significant increase in early GC detection rate (from none in 2015 to 13% in 2017, p = 0.03). Conclusions The protocolization of the referral for endoscopy associated with widespread use of HPSA test in the management of patients with dyspepsia, are successful strategies to decrease waiting lists for endoscopy and optimize the detection rate of pre-neoplastic lesions and early GC.

[Protocolized referral to endoscopy and Helicobacter pylori detected in stools aimed to decrease endoscopy waiting lists]. / La derivación protocolizada a endoscopía asociada a la detección de Helicobacter pylori mediante antígeno en deposiciones disminuye lista de espera para endoscopía y optimiza la detección de lesiones pre-malignas y cáncer gástrico incipiente.

Background Chile has one of the highest mortality rates by gastric cancer (GC) worldwide. Primary prevention of GC and detection of pre-neoplastic and early neoplastic lesions should be a national priority. Aim To assess the impact of the protocolization of endoscopy referral and the use of H. pylori stool antigen test (HPSA) in the management of dyspepsia to decrease the waiting list for endoscopy and increase the detection of gastric pre-neoplastic and early neoplastic lesions. Material and Methods We included all patients referred to the Endoscopy Unit of a regional hospital, from January 2015 to December 2017. We also included patients with known pre-neoplastic lesions and all those with first degree relatives with GC. We implemented protocols for referral of patients with dyspepsia considering the use of HPSA test, prioritizing to endoscopy those with a higher risk of GC. Results A total of 4,641 endoscopies and 2,631 HPSA tests were carried out. After the adoption of these protocols, we observed a 52% decrease in the waiting time for endoscopy. The GC detection rate in this period was 1.8 to 3.1 cases per 100 endoscopies. After the adoption of the protocols, we observed a significant increase in early GC detection rate (from none in 2015 to 13% in 2017, p = 0.03). Conclusions The protocolization of the referral for endoscopy associated with widespread use of HPSA test in the management of patients with dyspepsia, are successful strategies to decrease waiting lists for endoscopy and optimize the detection rate of pre-neoplastic lesions and early GC.

[Association between Helicobacter pylori genotype and the severity of gastritis in infected adults]. / Relación de la genotipificación de Helicobacter pylori con la forma e intensidad de la gastritis en población adulta portadora de patología gástrica benigna.

BACKGROUND: The damaging capacity of Helicobacter pylori is variable and depends, in part, on its genetic polymorphism. AIM: To study H pylori genes vacA, cagA and iceA and the relationship of these genotypes with the features of acute damage in chronic gastritis. MATERIAL AND METHODS: Gastric endoscopic biopsies were obtained in 75 adults for pathological study and genetic typification of H pylori by specific PCR. RESULTS: In only 64 cases, complete information was available. In 53 of these, there was H pylori infection demonstrated by PCR. Twenty one percent had infection by two or more H pylori strains, vacA gene had genotypes s2/m2, s1/m1 and s1/m2 in 36, 25 and 8% of cases respectively, cagA gene was present in 49% of infected patients. iceA gene had genotypes iceA 1 ad iceA 2 in 15 and 60% of patients respectively. The presence of cagA or alleles s1/m1 and s1/m2 of vacA gene was directly correlated with polymorphonuclear infiltration and the severity of epithelial damage. The genotype s2/m2 of vacA gene was significantly associated with a milder or absent mucosal damage. No association was found between iceA alleles and the pathological features of gastritis. CONCLUSIONS: Alleles of vacA and cagA genes of H pylori are associated with the severity of gastric mucosal damage.

[Point mutation of TP53 suppressor gene in pre-neoplastic and neoplastic lesions of the stomach]. / Mutación puntual del gen supresor de tumores TP53 en lesiones preneoplásicas y neoplásicas del estómago.

BACKGROUND: In the current model for the development of gastric cancer, regions of multifocal atrophic gastritis give rise to intestinal metaplasia, dysplasia and finally, adenocarcinoma. AIM: To study the frequency and characteristics of TP53 gene mutations in preneoplastic and neoplastic lesions of the stomach. MATERIAL AND METHODS: DNA sequencing of the TP53 gene was performed in 46 patients with gastric carcinoma. Normal mucosa, intestinal metaplasia and invasive adenocarcinoma tissues were obtained by scraping 6-micron histological sections from formalin-fixed and paraffin-embedded tissue. RESULTS: DNA sequencing of exons 5-9 of the TP53 gene demonstrated a mutation in 31% of patients. These findings were seen both in tumoral tissue (13 cases) and in intestinal metaplasia (2 cases). Most mutations were found in exons 5 and 8, and the majority of them were transitions (10 out of 19 mutations). DISCUSSION: Patients with gastric cancer showed a frequency of TP53 mutations similar to that previously communicated in populations with low gastric cancer risk. Moreover, there was a predominance of transitions, genetic alterations that are identified with carcinogenesis associated with N-nitrosamine compounds. Finally, mutations of TP53 gene were detected in areas of intestinal metaplasia.

[Microsatellite instability and loss of heterozygosity in neoplastic and preneoplastic gastric lesions]. / Inestabilidad microsatelital y pérdida de la heterocigocidad en lesiones neoplásicas y preneoplásicas gástricas.

BACKGROUND: Gastric cancer is the leading cause of cancer deaths in the general population in Chile, with mortality rates as high as 33.7 per 105 in males in the IX region. A chain of genetic and morphological events precedes the intestinal type of gastric carcinoma. One of them is the called multifocal atrophic gastritis often associated with intestinal metaplasia. AIM: To study the frequency of microsatellite instability (MSI) and loss of heterocigozity (LOH) in neoplastic and preneoplastic lesions of gastric carcinoma, especially intestinal metaplasia. MATERIAL AND METHODS: Ninety four gastric cancer biopsies were studied using laser capture microdissection, to obtain well defined cell populations from paraffin-embedded tissues: lymphocytes (control DNA), intestinal metaplasia and gastric cancer areas. Primer flanking microsatellite 15 highly polymorphic regions were used to study MSI and LOH. Radioactive PCR products were electrophoresed and exposed for autoradiography. RESULTS: LOH was observed in 83% of gastric carcinomas and in 54% areas containing intestinal metaplasia. The most commonly altered regions were the CA repeat associated with the p53 gene and the 3p21 region. High grade MSI was observed in 11.7% of gastric cancer preparations and 17% of intestinal metaplasia associated to cancer with MSI-H phenotype. CONCLUSIONS: MSI and LOH were frequently observed in intestinal metaplasia glands in patients with gastric carcinoma. The frequency of MSI-H phenotype in gastric patients was slightly lower than the one described in sporadic colorectal cancer not associated to HNPCC. The high incidence of genetic lesions in intestinal metaplasia area, support the idea that intestinal metaplasia is a genetically highly unstable cell population.

[Genetic changes in chronic gastritis: study of microsatellite instability and loss of heterozygosity]. / Alteraciones genéticas en gastritis crónica: estudio de inestabilidad microsatelital y pérdida de la heterocigocidad.

BACKGROUND: Multifocal chronic gastritis, associated to intestinal metaplasia, is considered a preneoplastic lesion, closely associated to intestinal type gastric cancer. AIM: To study the frequency of microsatellite instability (MSI) and loss of heterozygosity (LOH) in areas of chronic gastritis and intestinal metaplasia in gastric biopsies of patients without cancer. MATERIAL AND METHODS: Gastric biopsy samples from 34 patients without cancer (22 with multifocal atrophic gastritis and 12 with diffuse antral gastritis), were studied. Glands from areas of chronic gastritis and intestinal metaplasia and lymphocytes, were collected using laser microdissection of paraffin embedded samples. The analysis of 15 mono and dinucleotide microsatellites was used to assess LOH and MSI. RESULTS: LOH and MSI were found in some of the markers in 55% (12/22) and 59% (13/22) of cases with intestinal metaplasia, respectively. Only one of 12 areas with diffuse atrophic gastritis had MSI and a different area had LOH (p < 0.05 or less, when compared with areas of multifocal atrophic gastritis). Three areas of normal epithelium in patients with multifocal atrophic gastritis, also had alterations. Most of these alterations were concordant with adjacent areas with intestinal metaplasia. CONCLUSIONS: LOH and MSI was found in areas of intestinal metaplasia in more than half of the studied cases and in few areas of atrophic gastritis without intestinal metaplasia. These findings suggest that genotypic alterations may precede phenotypic modifications and that intestinal metaplasia is a preneoplastic lesion.