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Screening programs for colorectal cancer (CRC) are standard in most developed countries because they reduce mortality and are cost-effective. Within them, colonoscopy allows to directly visualize the colon and remove neoplastic lesions. However, it is an expensive exam with low adherence in asymptomatic individuals. The fecal occult blood test (FOBT) is a low-cost and risk-free method for the user, which results in a high rate of adherence, explaining its use in most screening programs. This article analyzes the effectiveness of different fecal occult blood tests in screening programs. The main conclusions are that the sensitivity of the guaiac-based chemical test for the detection of colorectal cancer is lower than that observed with qualitative and quantitative immunological tests. Automated quantitative methods allow objective readings independent of the operator and the reaction reading time, necessary for the analysis of large numbers of samples. The participation rate with immunological FOBTs is higher than with chemical ones, which is why they are preferred by the different countries that have screening programs. The use of quantitative tests allows stratification of symptomatic and asymptomatic patients at higher risk, in the screening programs.

Colorectal (CRC) is one of the most common types of cancer worldwide. Most tumors develop from an adenoma in a period of 10 to 15 years, but some may appear without previous adenomatous lesions. Seventy-five percent of colorectal cancers are sporadic, 20% have a family component (first or second-degree relatives with CRC) and 5% have a hereditary predisposition with a Mendelian pattern. The epidemiological evolution in the recent years in Chile has a worrisome evolution and the treatment costs of advanced stages are a burden for the healthcare system. We herein highlight the main Chilean medical and scientific contributions on the pathogenesis, early diagnosis, and treatment of CRC, which lead to its better understanding, and therefore better management, based on local evidence.

Germline pathogenic variants in the DNA mismatch repair genes (MMR): MLH1, MSH2, MSH6, and PMS2, are causative of Lynch syndrome (LS). However, many of the variants mapping outside the invariant splice site positions (IVS ± 1, IVS ± 2) are classified as variants of unknown significance (VUS). Three such variants (MLH1 c.588+5G>C, c.588+5G>T and c.677+5G>A) were identified in 8 unrelated LS families from Argentina, Brazil and Chile. Herein, we collected clinical information on these families and performed segregation analysis and RNA splicing studies to assess the implication of these VUS in LS etiology. Pedigrees showed a clear pattern of variant co-segregation with colorectal cancer and/or other LS-associated malignancies. Tumors presented deficient expression of MLH1-PMS2 proteins in 7/7 of the LS families, and MSI-high status in 3/3 cases. Moreover, RNA analyses revealed that c.588+5G>C and c.588+5G>T induce skipping of exon 7 whereas c.677+5G>A causes skipping of exon 8. In sum, we report that the combined clinical findings in the families and the molecular studies provided the evidences needed to demonstrate that the three MLH1 variants are causative of LS and to classify c.588+5G>C and c.677+5G>A as class 5 (pathogenic), and c.588+5G>T as class 4 (likely-pathogenic). Our findings underline the importance of performing clinical and family analyses, as well as RNA splicing assays in order to determine the clinical significance of intronic variants, and contribute to the genetic counseling and clinical management of patients and their relatives.

In Chile, the mortality from colorectal cancer has been on the rise. A national screening program based on a fecal immunochemical test was started in 2012 as an international collaboration with Japan. This case-control study was designed to identify the risk factors for colorectal cancer, with a goal of increasing the participation rate for colorectal cancer screening. In accordance with the Strengthening the Reporting of Observational Studies in Epidemiology guidelines, we conducted a case-control study from 2012 to 2017; 23 845 asymptomatic participants were enrolled in the study. Participants who were fecal immunochemical test-positive or had a family history of colorectal cancer underwent a colonoscopy. We analyzed the odds ratio of the risk factors for colorectal cancer, including sex, age, family history, BMI, hypertension, diabetes, regular use of nonsteroidal anti-inflammatory drugs, alcohol consumption, smoking, physical activity, and daily intake of certain food items. For the screening program, 202 cases of colorectal cancer were detected, and 195 of them were evaluated pathologically after resection. Of these, 173 cases (88.7%) had colorectal cancer stage 0/1, 151 (77.4%) of which were treated with endoscopic resection. In the multivariate analysis, male sex, family history of colorectal cancer, and low intake of cereals or fibers were closely related to a high colorectal cancer incidence. Moreover, participants in their 60s and 70s had a higher incidence of colorectal cancer than those in their 50s. These results suggest that intensive screening of the high-risk population can help in improving the detection of colorectal cancer, whereas higher consumption of cereals or fibers can be effective in preventing its onset.

Introduccion: PIPAC ( Pressurized Intraperitoneal Aerosol Chemotherapy ) Es una tecnica que, via laparoscopia, permite administrar quimioterapia en aerosol intraperitoneal, para el tratamiento de la carcinomatosis, ya sea para disminuir masa tumoral y aumentar la resecabilidad, o como paliacion sintomatica. Objetivo: Presentar los dos primeros casos de PIPAC en Chile, las consideraciones tecnicas y revision de la literatura. Pacientes y Metodo: Se describe la forma en que un programa PIPAC fue implementado en Clinica Las Condes. S e describe la tecnica. Este procedimiento se realizo en dos pacientes, ambas portadoras de carcinomatosis con ascitis refractaria. Resultados: No hubo complicaciones. Alta a las 24 horas. Ambas pacientes presentaron disminucion de la ascitis, la que se ha mantenido a los seis meses de seguimiento. Discusion: PIPAC es una tecnica emergente, que ha demostrado ser segura, con escasas complicaciones, cuya indicacion incluye carcinomatosis por cancer de colon y ovario y que se esta extendiendo a pancreas, via biliar y estomago. Su rol exacto esta por definirse. Conclusiones: PIPAC es una tecnica factible de realizar en nuestro pais; sus resultados preliminares son alentadores y exentos de complicaciones.

Background. Lynch syndrome is the most common genetic predisposition for hereditary cancer. Carriers of pathogenic changes in mismatch repair (MMR) genes have an increased risk of developing colorectal (CRC), endometrial, ovarian, urinary tract, prostate, and other cancers, depending on which gene is malfunctioning. In Lynch syndrome, differences in cancer incidence (penetrance) according to the gene involved have led to the stratification of cancer surveillance. By contrast, any differences in penetrance determined by the type of pathogenic variant remain unknown. Objective. To determine cumulative incidences of cancer in carriers of truncating and missense or aberrant splicing pathogenic variants of the MLH1 and MSH2 genes. Methods. Carriers of pathogenic variants of MLH1 (path_MLH1) and MSH2 (path_MSH2) genes filed in the Prospective Lynch Syndrome Database (PLSD) were categorized as truncating or missense/aberrant splicing according to the InSiGHT criteria for pathogenicity. Results. Among 5199 carriers, 1045 had missense or aberrant splicing variants, and 3930 had truncating variants. Prospective observation years for the two groups were 8205 and 34,141 years, respectively, after which there were no significant differences in incidences for cancer overall or for colorectal cancer or endometrial cancers separately. Conclusion. Truncating and missense or aberrant splicing pathogenic variants were associated with similar average cumulative incidences of cancer in carriers of path MLH1 and path_MSH2.

Colorectal cancer (CRC) is one of the most common cancers in Latin America and the Caribbean, with the highest rates reported for Uruguay, Brazil and Argentina. We provide a global snapshot of the CRC patterns, how screening is performed, and compared/contrasted to the genetic profile of Lynch syndrome (LS) in the region. From the literature, we find that only nine (20%) of the Latin America and the Caribbean countries have developed guidelines for early detection of CRC, and also with a low adherence. We describe a genetic profile of LS, including a total of 2,685 suspected families, where confirmed LS ranged from 8% in Uruguay and Argentina to 60% in Peru. Among confirmed LS, path_MLH1 variants were most commonly identified in Peru (82%), Mexico (80%), Chile (60%), and path_MSH2/EPCAM variants were most frequently identified in Colombia (80%) and Argentina (47%). Path_MSH6 and path_PMS2 variants were less common, but they showed important presence in Brazil (15%) and Chile (10%), respectively. Important differences exist at identifying LS families in Latin American countries, where the spectrum of path_MLH1 and path_MSH2 variants are those most frequently identified. Our findings have an impact on the evaluation of the patients and their relatives at risk for LS, derived from the gene affected. Although the awareness of hereditary cancer and genetic testing has improved in the last decade, it is remains deficient, with 39%–80% of the families not being identified for LS among those who actually met both the clinical criteria for LS and showed MMR deficiency. Radium Hospital Foundation (Oslo, Norway)

Objetivo: Analizar los resultados quirúrgicos y oncológicos de pacientes con adenocarcinoma de recto (AR) operados con asistencia robótica.Materiales y métodos: Cohorte prospectiva entre 2014-2019. Criterios de inclusión: pacientes con AR primario, sometidos a una resección de recto con asistencia robótica con intención curativa. Criterios de exclusión: histología no adenocarcinoma. Evaluación de datos clínico-quirúrgicos. Análisis estadístico descriptivo.Resultados: Se incluyeron 37 pacientes; 20 (54%) fueron hombres y la edad promedio fue 58,7 años. La distancia promedio desde el margen anal al borde distal del tumor fue 6,6 cm (i: 2 - 12 cm). La quimioradioterapia (neoadyuvancia) se indicó en 26 pacientes. La cirugía más frecuente fue la resección anterior baja de recto y el tiempo operatorio promedio fue 266 minutos. Se realizaron dos conversiones a laparotomía. Una o más complicaciones se observaron en 17 (45,9%) pacientes, 9 de ellos fueron Clavien-Dindo III ó IV y se reoperaron 5 pacientes (13%). No hubo transfusiones sanguíneas ni mortalidad post-operatoria. La estancia hospitalaria postoperatoria promedio fue 9,6 días (i: 3 – 34 d). El promedio de linfonodos resecados fue 15 (i 4 - 45). Los márgenes quirúrgicos fueron negativos en todos los pacientes. Se restituyó el tránsito intestinal en 28/32 (87,5%) pacientes. El promedio de seguimiento fue 21 meses (1-56), la sobrevida global y libre de enfermedad fue 100%.Discusión y conclusión: La proctectomía con asistencia robótica ha demostrado ser segura en términos de resultados quirúrgicos tempranos y en criterios oncológicos de la pieza operatoria.

Colorectal cancer (CRC) is one of the most common cancers worldwide. As with other cancers, CRC is a multifactorial disease due to the combined effect of genetic and environmental factors. Most cases are sporadic, but a small proportion is hereditary, estimated at around 5-10%. In both, the tumor interacts with heterogeneous cell populations, such as endothelial, stromal, and immune cells, secreting different signals (cytokines, chemokines or growth factors) to generate a favorable tumor microenvironment for cancer cell invasion and metastasis. There is ample evidence that inflammatory processes have a role in carcinogenesis and tumor progression in CCR. Different profiles of cell activation of the tumor microenvironment can promote pro or anti-tumor pathways; hence they are studied as a key target for the control of cancer progression. Additionally, the intestinal mucosa is in close contact with a microorganism community, including bacteria, bacteriophages, viruses, archaea, and fungi composing the gut microbiota. Aberrant composition of this microbiota, together with alteration in the diet‐derived microbial metabolites content (such as butyrate and polyamines) and environmental compounds has been related to CRC. Some bacteria, such as pks+ Escherichia coli or Fusobacterium nucleatum, are involved in colorectal carcinogenesis through different pathomechanisms including the induction of genetic mutations in epithelial cells and modulation of tumor microenvironment. Epithelial and immune cells from intestinal mucosa have Pattern-recognition receptors and G-protein coupled receptors (receptor of butyrate), suggesting that their activation can be regulated by intestinal microbiota and metabolites. In this review, we discuss how dynamics in the gut microbiota, their metabolites, and tumor microenvironment interplays in sporadic and hereditary CRC, modulating tumor progression.

Colorectal cancer (CRC) is the second most frequent neoplasm in Chile and its mortality rate is rising in all ages. However, studies characterizing CRC according to the age of onset are still lacking. This study aimed to identify clinical, pathological, and molecular features of CRC in Chilean patients according to the age of diagnosis: early- (≤50 years, EOCRC), intermediate- (51–69 years, IOCRC), and late-onset (≥70 years, LOCRC). The study included 426 CRC patients from Clinica Las Condes, between 2007 and 2019. A chi-square test was applied to explore associations between age of onset and clinicopathological characteristics. Body Mass Index (BMI) differences according to age of diagnosis was evaluated through t-test. Overall (OS) and cancer-specific survival (CSS) were estimated by the Kaplan–Meier method. We found significant differences between the age of onset, and gender, BMI, family history of cancer, TNM Classification of Malignant Tumors stage, OS, and CSS. EOCRC category was characterized by a family history of cancer, left-sided tumors with a more advanced stage of the disease but better survival at 10 years, and lower microsatellite instability (MSI), with predominant germline mutations. IOCRC has shown clinical similarities with the EOCRC and molecular similarities to the LOCRC, which agrees with other reports.

Lynch syndrome (LS) results from pathogenic variants in the mismatch repair (MMR) genes and is the most common hereditary cancer syndrome, affecting an estimated 1 in 300 individuals. Pathogenic variants in each of the MMR genes path_MLH1, path_MSH2, path_MSH6, and path_PMS2 result in different risks for cancers in organs including the colorectum, endometrium, ovaries, stomach, small bowel, bile duct, pancreas, and upper urinary tract. Accurate estimates of these risks are essential for planning appropriate approaches to the prevention or early diagnosis of cancers but the robustness of previous studies has been limited by factors including retrospective design,1,2 lack of validation in independent cohorts,3-5 and inconsistent classification of genetic variants. Unexpected findings from previous studies have included path_MLH1 and path_MSH2 carriers appearing to have a lifetime risk of colorectal cancer (CRC) of approximately 50%, despite surveillance colonoscopy,6-8 and that shorter intervals between colonoscopies do not seem to reduce the incidence of CRC in LS.9,10 These findings challenge the assumptions that CRC in LS usually develops from a noninfiltrative adenoma precursor and that CRC can be prevented by colonoscopic detection and removal of adenomas in the colon and rectum. Additionally, previous studies in the Prospective Lynch Syndrome Database (PLSD) have shown no increase in cancer risk in path_PMS2 carriers before 40 years of age and, although observation years were limited in older path_PMS2 carriers, LS-associated cancers other than endometrial and prostate were not observed.6-8 In this study we collected prospective data from a new large cohort of path_MMR carriers to validate previous findings from PLSD. We also updated information on the original cohort to ensure consistent classification of pathogenicity of MMR gene variants. We then combined both data sets, providing larger numbers that allowed us to derive more precise risk estimates for cancers in LS categorized by gene and gender.

Screening programs for colorectal cancer (CRC) are standard in most developed countries because they reduce mortality and are cost-effective. Within them, colonoscopy allows to directly visualize the colon and remove neoplastic lesions. However, it is an expensive exam with low adherence in asymptomatic individuals. The fecal occult blood test (FOBT) is a low-cost and risk-free method for the user, which results in a high rate of adherence, explaining its use in most screening programs. This article analyzes the effectiveness of different fecal occult blood tests in screening programs. The main conclusions are that the sensitivity of the guaiac-based chemical test for the detection of colorectal cancer is lower than that observed with qualitative and quantitative immunological tests. Automated quantitative methods allow objective readings independent of the operator and the reaction reading time, necessary for the analysis of large numbers of samples. The participation rate with immunological FOBTs is higher than with chemical ones, which is why they are preferred by the different countries that have screening programs. The use of quantitative tests allows stratification of symptomatic and asymptomatic patients at higher risk, in the screening programs.

Molecular classification of colorectal cancer is difficult to implement in clinical settings where hundreds of genes are involved, and resources are limited. This study aims to characterize the molecular subtypes of patients with sporadic colorectal cancer based on the three main carcinogenic pathways microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and chromosomal instability (CIN) in a Chilean population. Although several reports have characterized colorectal cancer, most do not represent Latin-American populations. Our study includes 103 colorectal cancer patients who underwent surgery, without neoadjuvant treatment, in a private hospital between 2008 and 2017. MSI, CIN, and CIMP status were assessed. Frequent mutations in KRAS, BRAF, and PIK3CA genes were analyzed by Sanger sequencing, and statistical analysis was performed by Fisher’s exact and/or chi-square test. Survival curves were estimated with Kaplan–Meier and log-rank test. Based on our observations, we can classify the tumors in four subgroups, Group 1: MSI-high tumors (15%) are located in the right colon, occur at older age, and 60% show a BRAF mutation; Group 2: CIN-high tumors (38%) are in the left colon, and 26% have KRAS mutations. Group 3: [MSI/CIN/CIMP]-low/negative tumors (30%) are left-sided, and 39% have KRAS mutations; Group 4: CIMP-high tumors (15%) were more frequent in men and left side colon, with 27% KRAS and 7% presented BRAF mutations. Three percent of patients could not be classified. We found that CIMP-high was associated with a worse prognosis, both in MSI-high and MSI stable patients (p = 0.0452). Group 3 (Low/negative tumors) tend to have better overall survival compared with MSI-high, CIMP-high, and CIN-high tumors. This study contributes to understanding the heterogeneity of tumors in the Chilean population being one of the few characterizations performed in Latin-America. Given the limited resources of these countries, these results allow to improve molecular characterization in Latin-American colorectal cancer populations and confirm the possibility of using the three main carcinogenic pathways to define therapeutic strategies.

Colorectal (CRC) is one of the most common types of cancer worldwide. Most tumors develop from an adenoma in a period of 10 to 15 years, but some may appear without previous adenomatous lesions. Seventy-five percent of colorectal cancers are sporadic, 20% have a family component (first or second-degree relatives with CRC) and 5% have a hereditary predisposition with a Mendelian pattern. The epidemiological evolution in the recent years in Chile has a worrisome evolution and the treatment costs of advanced stages are a burden for the healthcare system. We herein highlight the main Chilean medical and scientific contributions on the pathogenesis, early diagnosis, and treatment of CRC, which lead to its better understanding, and therefore better management, based on local evidence.

Background : Colorectal Cancer Screening Programs (CRCSP) are widely accepted in developed countries. Unfortunately, financial restrictions, low ad- herence rate and variability on colonoscopy standardization hamper the imple- mentation of CRCSP in developing countries. Aim : To analyze a multicentric pilot model of CRCSP in Chile. Material and Methods: A prospective model of CRCSP was carried out in three cities, from 2012 to 2015. The model was based on CRC risk assessment and patient education. Health care personnel were trained about logistics and protocols. The endoscopy team was trained about colonoscopy standards. A registered nurse was the coordinator in each center. We screened asymptomatic population aged between 50 and 75 years. Immunological fecal occult blood test (FIT) was offered to all participants. Subjects with positive FIT underwent colonoscopy. Results : A total of 12,668 individuals were enrolled, with a FIT compliance rate of 93.9% and 2,358 colonoscopies were performed. Two hundred and fifty high-risk adenomas and 110 cancer cases were diagnosed. One patient died before treatment due to car- diovascular disease, 74 patients (67%) underwent endoscopic resection and 35 had surgical treatment. Ninety one percent of patients had an early stage CRC (0-I-II). Among colonoscopy indicators, 80% of cases had an adequate bowel preparation (Boston > 6), cecal intubation rate was 97.7%, adenoma detection rate was 36.5%, and in 94.5% of colonoscopies, withdrawal time was adequate (> 8 min). Conclusions: This CRCS pilot model was associated to a high rate of FIT return and colonoscopy quality standards. Most CRCs detected with the program were treated by endoscopic resection

Background: Colorectal cancer (CRC) is an heterogeneous disease. Three carcinogenic pathways determine its molecular profile: microsatellite instability (MSI), chromosomal instability (CIN) and CpG island methylator phenotype (CIMP). Based on the new molecular classification, four consensus CRC molecular subtypes (CMS) are established, which are related to clinical, pathological and biological characteristics of the tumor. Aim: To classify Chilean patients with sporadic CRC according to the new consensus molecular subtypes of carcinogenic pathways. Material and Methods: Prospective analytical study of 53 patients with a mean age of 70 years (55% males) with CRC, operated at a private clinic, without neoadjuvant treatment. From normal and tumor tissue DNA of each patient, CIN, MSI and CIMP were analyzed. Combining these variables, tumors were classified as CMS1/MSI-immune, CMS2/canonical, CMS3/metabolic and CMS4/mesenchymal. Results: CMS1 tumors (19%) were located in the right colon, were in early stages, had MMR complex deficiencies and 67% had an activating mutation of the BRAF oncogene. CMS2 tumors (31%) were located in the left colon, had moderate differentiation, absence of vascular invasion, lymphatic and mucin. CMS3 tumors (29%) were also left-sided, with absence of vascular and lymphatic invasion, and 29% had an activating mutation of the KRAS oncogene. CMS4 tumors (21%) showed advanced stages and presence of metastases. Conclusions: This new molecular classification contributes to understanding the heterogeneity of tumors. It is possible to differentiate molecular subgroups of a single pathological diagnosis of adenocarcinoma, opening the door to personalized medicine.

High incidence of Rho Cdc42-GTPase overexpression has been found in Colorectal Cancer (CRC) samples, suggesting its potential role in tumor development. However, no conclusive studies have shown the lack of mutations and/or copy number of Cdc42 gene in this type of samples. To understand mutation/deletion and copy number status of Cdc42 gene, CRC patients were evaluated for both parameters. More than Cdc42 mutants, single-nucleotide variants were found. Analysis of regions flanking the Cdc42 gene showed allelic imbalance; 58.7% were loss of heterozygosity (LOH) positive and 14.8% presented microsatellite instability. The highest LOH percentage was located between microsatellite markers D1S199 and D1S2674, where the Cdc42 gene is located. No association between gender, age, and tumor stage was found. LOH validation through gene dosage analysis showed most CRC patients with allelic imbalance also presented a low gene dosage of Cdc42, although equal amounts of Cdc42 mRNA were detected in all samples. Although changes in Cdc42 expression were not found in any condition, Cdc42 activation was different between high and normal gene dosage samples, but not between samples with normal and low copy number. Low dosage of Cdc42 was also not related to changes in methylation status at the Cdc42 promoter region. Results suggest that low copy of Cdc42 gene is not associated with Cdc42 protein dysfunction in CRC patients.

We aimed to assess the current genetics practice to manage patients with Lynch syndrome (LS) across Latin America. A Latin American LS survey was sent out to 52 centres/registries, comprising a total of 12 countries from the region. Overall, 33 centres completed the survey, of which the oldest LS registry was established in 1992 in Sao Paulo (Brazil), and the youngest this year in San Jose (Costa Rica). In total, 87% (26/30) of the participating centres/registries belonging to the nine countries are performing genetic testing. Overall, 1352 suspected families were sequenced. Pathogenic variants were identified in 34% of the families, with slightly differing distribution of variants between females and males. Path_MLH1 variants were identified in 39% of females and 50% of males (p = 0.023), while path_MSH2 were identified in 37% of females and males, followed by path_PMS2 in 11% of females and 8% of males, path_MSH6 in 13% of females and 3% of males (p 0.001) and path_EPCAM in 0.3% of females and 2% of males. In Latin America, 9 of 12 (75%) participating countries had implemented healthcare for LS. LS screening is inconsistently applied within Latin America healthcare systems because of structural differences in the healthcare systems between the countries.

Resumen Introducción: La resección anterior ultrabaja interesfintérica (RAUBIE), permite preservar la función esfinteriana en pacientes seleccionados con cáncer de recto (CR). No obstante, puede producir alteraciones en la función evacuatoria y esfinteriana. Objetivo: Analizar los resultados oncológicos y funcionales luego de una RAUBIE. Material y Método: Estudio observacional, analítico, transversal, durante el período 2007 a 2016. Criterios de inclusión: Pacientes sometidos a RAUBIE por CR con intención curativa. Todos los pacientes tuvieron un seguimiento el año 2017. Para la evaluación funcional se usó la escala de Jorge-Wexner, LARS y Kirwan. Análisis estadístico: Estadística descriptiva y método de Kaplan-Meier. Resultados: De 21 pacientes; catorce (67%) fueron varones, edad promedio: 59 años. Ubicación tumoral: 4 cm (2-6 cm) del margen anal. Dieciocho (85,7%) pacientes recibieron neoadyuvancia. Todos los márgenes quirúrgicos distales y radiales fueron negativos. Un paciente (4,8%) tuvo metástasis a distancia y no hubo recurrencia locorregional. Con una mediana de seguimiento de 76,3 (9,8-126,8) meses, la sobrevida global y libre de enfermedad a 5 años fue de: 100% y 95% (IC: 90,1-99,9%), respectivamente. Con una mediana de seguimiento de 90 meses (21,7-124,2); se realizó la evaluación funcional a 15/21 pacientes. El puntaje de Jorge-Wexner tuvo una mediana de 13 (4-17) puntos, la escala de LARS de 34 puntos y en la escala de Kirwan, cuatro pacientes (26,7%) mostraron una buena función (Kirwan I-II). Conclusión: Si bien los resultados oncológicos de los pacientes sometidos a una RAUBIE son satisfactorios, se debería tomar en cuenta los resultados funcionales al momento de proponer esta alternativa quirúrgica.

Objetivo: Analizar la frecuencia y tipo de tumores asociados en pacientes con poliposis adenomatosa familiar clásica (PAFc) sometidos a una colectomía profiláctica. Materiales y Métodos: Estudio de cohorte. Desde el registro de cáncer colorrectal (CCR) hereditario, se identificaron las familias con PAFc, y de estas a los pacientes que se les practicó una colectomía total con anastomosis íleorrectal (CT-AIR) o proctocolec-tomía restauradora (PCTR), desde 1999 al 2014. En el seguimiento se analizaron los tumores asociados y su mortalidad. Resultados: Se identificaron 27 pacientes, de los cuales 18 (66,7%) fueron sometidos a CT-AIR y 9 (33,3%) a PCTR. Al momento de la cirugía, 4 pacientes presentaban CCR (15%) y 5 tenían tumores extracolónicos (osteomas). En un seguimiento promedio de 49,4 meses (i: 2 y 178) se diagnosticaron: adenomas del tracto digestivo en 17 (63%) pacientes, de éstos 2 requirieron una proctectomía y 3 resecciones de adenomas duodenales. Ocho pacientes desarrollaron tumores desmoides (30%), y 3 de ellos fueron sometidos a una cirugía. Un paciente presentó un tumor extradigestivo (cáncer de tiroides) y sólo 8/27 (29,6%) pacientes no desarrollaron otros tumores. Un paciente falleció por progresión de su CCR. Discusión: En esta serie se confirma que la mayoría de los pacientes con PAFc seguirán desarrollando neoplasias después de su colectomía. conclusiones: La extirpación del colon y/o recto permitió evitar el desarrollo de CCR. Sin embargo, dos tercios de los pacientes presentaron otros tumores en quienes su seguimiento permitió una detección y tratamiento temprano.

Lynch syndrome (LS) is associated with the highest risk of colorectal (CRC) and several extracolonic cancers. In our effort to characterize LS families from Latin America, this study aimed to describe the spectrum of neoplasms and cancer risk by gender, age and gene, and survival in 34 Chilean LS families. Of them, 59% harbored path_MLH1, 23% path_MSH2, 12% path_PMS2 and 6% path_EPCAM variants. A total of 866 individuals at risk were identified, of which 213 (24.6%) developed 308 neoplasms. In males, CRC was the most common cancer (72.6%), while females showed a greater frequency of extracolonic cancers (58.4%), including uterus and breast (p &lt, 0.0001). The cumulative incidence of extracolonic cancers was higher in females than males (p = 0.001). Path_MLH1 variants are significantly more associated with the development of CRC than extracolonic tumors (59.5% vs. 40.5%) when compared to path_MSH2 (47.5% vs. 52.5%) variants (p = 0.05018). The cumulative incidence of CRC was higher in path_MLH1/path_MSH2 carriers compared to path_PMS2 carriers (p = 0.03). In addition, path_MSH2 carriers showed higher risk of extracolonic tumors (p = 0.002). In conclusion, this study provides a snapshot of the LS profile from Chile and the current LS-associated diagnostic practice and output in Chile. Categorizing cancer risks associated with each population is relevant in the genetic counselling of LS patients.

Background: In Chile, a national colorectal cancer (CRC) screening program using immunochemical fecal occult blood tests and colonoscopy was started in 2012 as an international collaboration between Chile and Japan. In the present study, we quantified exosomes in the peripheral blood and evaluated the implication of the results for CRC screening. Methods: A total of 25 peripheral plasma samples from the participants of CRC screening in Punta Arenas, Chile, were analyzed for exosomes. Results: Plasma exosomes were obtained from 5 participants with adenocarcinoma (4 pTis and 1 pT1), 8 with high-grade adenoma, 4 with low-grade adenoma, 4 with hyperplastic polyps, and 4 with normal findings. Participants with adenocarcinoma had significantly higher amounts of plasma exosomes (2.1–3.2 fold) than participants with normal findings, hyperplastic polyps, or low-grade adenoma (p = 0.016, p = 0.0034, and p = 0.0042 respectively; Tukey’s multiple comparisons test). The size of the representative lesion, the number of lesions, and the sum of those 2 factors in each participant correlated significantly with the exosome amounts (r = 0.56, r = 0.58, and r = 0.72, respectively; p < 0.01; Spearman’s correlation coefficient test). Conclusions: This pilot study demonstrated that quantification of plasma exosomes is a potential alternative screening method for detecting individuals with a high risk of colorectal malignancy.

Aim To describe the long-term outcomes of adipose-mesenchymal stem cells, platelet-rich plasma, and endorectal advancement flaps in patients with Perineal Crohn's Disease. Method This was a single-center, prospective, observational pilot study performed between March 2013 and December 2016. The study included adult patients diagnosed with Perianal Crohn's Disease (with complex perianal fistulas) refractory to previous surgical and/or biological treatment. Patients underwent surgical treatment in two stages. Stage 1: Fistula mapping, drainage, seton placement and lipoaspiration to obtain adipose-mesenchymal stem cells were performed. Stage 2: The setons were removed, and the fistula tract was debrided. A small endorectal advancement flap was created, with closure of the previous internal fistula opening. Then, 100-120 million adipose-mesenchymal stem cells mixed with platelet-rich plasma were injected into the internal fistula opening and fistula tract. Results The study included nine patients (seven females), with a median age of 36 years (r = 23-57). Eleven fistula tracks were treated, of which, two were pouch-vaginal fistulas. The median follow-up period was 31 months (r=21-37). At the end of the follow-up period, 10/11 (91%) fistulas were completely healed and 1/11 (9%) was partially healed. At the end of this period, there was no evidence of fistula relapse or adverse reactions in any patients. The Perianal Disease Activity Index and Inflammatory Bowel Disease Questionnaire scores significantly improved after the procedure. Conclusion Combined therapy with adipose-mesenchymal stem cells, platelet-rich plasma and endorectal advancement flaps yielded good results in patients with refractory Perineal Crohn's Disease. This article is protected by copyright. All rights reserved.

BACKGROUND In Chile, mortality from colorectal cancer (CRC) has increased rapidly. To help address this issue, the Prevention Project for Neoplasia of the Colon and Rectum (PRENEC) program was initiated in 2012 with intensive support from Tokyo Medical and Dental University (TMDU) in Tokyo, Japan, as part of an international collaboration. METHODS From June 2012 to July 2014, a total of 10,575 asymptomatic participants were enrolled in PRENEC. Participants with positive immunochemical fecal occult blood test (iFOBT) results or a family history of CRC underwent colonoscopy. The colonoscopy results from a similar, previous project in Chile (PREVICOLON) were compared with those from PRENEC. Furthermore, the initial colonoscopies of 1562 participants in PRENEC were analyzed according to whether the colonoscopists were from TMDU or Chile. RESULTS The complete colonoscopy, adenoma detection, and cancer detection rates were 88.0%, 26.7%, and 1.1%, respectively, in PREVICOLON, while the corresponding values were 94.4%, 41.8%, and 6.0%, respectively, in PRENEC. In PRENEC, 107 cases of CRC were detected, amounting for 1.0% of all participants. Considering initial colonoscopies in PRENEC, the complete colonoscopy, adenoma detection, and cancer detection rates were 97.4%, 45.3%, and 9.3%, respectively, for physicians at TMDU and 93.3%, 41.5%, and 5.1%, respectively for Chilean physicians. The detection rates of intramucosal cancer were 7.3% and 3.7%, respectively, for TMDU and Chilean physicians. CONCLUSIONS Quality indicators of colonoscopy substantially improved from PREVICOLON to PRENEC. The assessments made by Chilean physicians alone were improved in PRENEC, but remained better in the TMDU group. Moreover, physicians from TMDU detected more CRCs than Chilean physicians, especially at earlier stages. Cancer 2016;122:71–77. © 2015 American Cancer Society.

Background: In Chile, colorectal cancer (CRC) is often diagnosed in late stages. Thus, surgical treatment must be complemented with chemotherapy. KRAS mutations and microsatellite instability have been detected in these tumors. However, the response to treatment in patients without KRAS mutations varies and requires a better understanding. Aim: To determine the frequency and distribution of somatic point mutations in KRAS, BRAF and PIK3CA genes and microsatellite instability status (MSI) in patients with colon cancer (CC). Material and Methods: A prospective observational study of patients undergoing surgery for colon cancer. Tumor-derived DNA was analyzed by polymerase chain reaction (PCR) for the most frequent mutations of KRAS, BRAF and PIK3CA. PCR was also used to analyze MSI. Results: Fifty-eight patients with sporadic CC were analyzed, 16 showed KRAS mutations (G12R, G12D, G12V, G13D) and out of the 42 patients that did not show any mutation, 10 had mutations in BRAF (V600E) and PIK3CA (E542K, E545D, E545K, Q546E, H1047R). BRAF mutations alone or in combination with PIK3CA mutations were observed in 27% of high MSI tumors and in 2% of tumors without instability (p < 0.049). A higher percentage of high MSI tumors were located in the right colon (p < 0.001), and showed BRAF mutation (p < 0.020). Conclusions: The highest percentage of high MSI and BRAF mutations was observed in the right colon. Therefore, this study suggests the presence of different molecular features between right and left colon tumors that should be considered when defining the therapeutic management.

Background: The molecular testing of KRAS mutation status in metastatic colorectal cancer patients is mandatory to identify patients eligible for anti- epidermal growth factor receptor monoclonal antibody therapy. Aim: To report the frequency of KRAS gene mutations in Chilean patients with colorectal cancer (CRC). Material and Methods: A cohort of 262 Chilean patients with CRC aged 26 to 90 years (53% males), was studied. KRAS mutation status was analyzed by real-time polymerase chain reaction and correlated with clinicopathological data. Results: Ninety-eight patients (37%) were positive for KRAS mutations. G12D was the most common mutation with a frequency of 36.7%, followed by G12V (25.5%), G13D (17.3%), G12A (7.1%), G12C (6.1%), G12S (5.1%) and G12R (2%). The frequency of the mutation in left, right colon and rectal tumors was 37.8, 32.6 and 44.9%, respectively. Among tumors with mutations, 86.7% were well or moderately differentiated tumors and the rest were poorly differentiated. No significant associations between KRAS gene mutations and other clinicopathological features of the tumor were observed. Conclusions: The frequencies of KRAS mutations reported in this study are similar to frequencies reported for European and North-American populations, lower than in a Spanish study and higher than in a Peruvian study. (Rev Med Chile 2014; 142: 1407-1414)

Background: Genetic counselling and testing for Lynch syndrome (LS) have recently been introduced in several Latin America countries. We aimed to characterize the clinical, molecular and mismatch repair (MMR) variants spectrum of patients with suspected LS in Latin America. Methods: Eleven LS hereditary cancer registries and 34 published LS databases were used to identify unrelated families that fulfilled the Amsterdam II (AMSII) criteria and/or the Bethesda guidelines or suggestive of a dominant colorectal (CRC) inheritance syndrome. Results: We performed a thorough investigation of 15 countries and identified 6 countries where germline genetic testing for LS is available and 3 countries where tumor testing is used in the LS diagnosis. The spectrum of pathogenic MMR variants included MLH1 up to 54%, MSH2 up to 43%, MSH6 up to 10%, PMS2 up to 3% and EPCAM up to 0.8%. The Latin America MMR spectrum is broad with a total of 220 different variants which 80% were private and 20% were recurrent. Frequent regions included exons 11 of MLH1 (15%), exon 3 and 7 of MSH2 (17 and 15%, respectively), exon 4 of MSH6 (65%), exons 11 and 13 of PMS2 (31% and 23%, respectively). Sixteen international founder variants in MLH1, MSH2 and MSH6 were identified and 41 (19%) variants have not previously been reported, thus representing novel genetic variants in the MMR genes. The AMSII criteria was the most used clinical criteria to identify pathogenic MMR carriers although microsatellite instability, immunohistochemistry and family history are still the primary methods in several countries where no genetic testing for LS is available yet. Conclusion: The Latin America LS pathogenic MMR variants spectrum included new variants, frequently altered genetic regions and potential founder effects, emphasizing the relevance implementing Lynch syndrome genetic testing and counseling in all of Latin America countries., Radium Hospital Foundation (Oslo, Norway) in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript, Helse Sør-Øst (Norway) in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript, the French Association Recherche contre le Cancer (ARC) in the analysis, and interpretation of data, the Groupement des Entreprises Françaises dans la Lutte contre le Cancer (Gefluc) in the analysis, and interpretation of data, the Association Nationale de la Recherche et de la Technologie (ANRT, CIFRE PhD fellowship to H.T.) in the analysis, and interpretation of data and by the OpenHealth Institute in the analysis, and interpretation of data. Barretos Cancer Hospital received financial support by FINEP-CT-INFRA (02/2010), info:eu-repo/semantics/publishedVersion

Background: The incidence and prevalence of Inflammatory Bowel Disease (IBD) has increased. Aim: To determine demographic and clinical characteristics of patients with IBD in a Chilean private hospital. Patients and methods: Review of a prospective registry of patients with IBD, started on 2012. It includes clinical, imaging, endoscopical and pathological information of patients. Results: Data of 316 patients with IBD, aged 16 to 86 years (56% females), were analyzed. Ulcerative Colitis (UC), Crohn´s and non-classifiable IBD were diagnosed in 230, 77 and 9 patients, respectively. The disease was diagnosed in 82% of patients in the period between 2002 and 2012. There was a peak in the diagnosis of both UC and CD between 20 and 39 years of age, without gender differences. The disease switched from UC to CD in six patients. In four, there was a change in disease behavior. Thirty eight patients were treated with biological therapy. The median lapse between the diagnosis and the use of biological therapy was 1 year in patients diagnosed after 2007, compared with 5.5 years among those patients diagnosed before 2007 (p=0.001). There was a trend towards a higher requirement of surgery until 2006. Posteriorly there was a stabilization of the requirement, concomitant with the incorporation of biological therapy. Conclusions: An adequate registry of IBD patients is necessary to improve demographic and clinical characteristics. A national registry is needed to assess the epidemiological changes of IBD in Chile.

Introduction Pelvic floor dyssynergia (PPD) is a common cause of outlet obstruction constipation. Treatment for this condition is based on pelvi-perineal re-education (PPR). The aim of this study was to evaluate the results of PPR on patients with PPD. Methods Patients with the diagnosis of PPD were included. The study was conducted between 2010 and 2011. PPR was performed by specialised kinesiologists. Prior and after treatment a constipation questionnaire was performed (KESS) (scale from 0 to 39 points, a higher score is associated with more symptom severity). KESS score before and after PPR were compared. Mann–Whitney–Wilcoxon rank sum test for paired samples was used for statistical analysis, P value Results Thirteen patients were included (11 women), and mean age was 44.3 years (range: 18–76). Mean total KESS score prior and after PPR were 19.6 (SD: 5.8) and 12.6 (SD: 6.3), respectively ( P =.002). Frequency of bowel movements, stool consistency, abdominal pain, and abdominal bloating did not present statistically significant changes before and after treatment. Use of laxatives, enemas and/or digitations, as well as unsuccessful evacuation, feelings of incomplete evacuation improved significantly. Total evacuation time (before 1.53 vs after 1; P =.012) and difficult evacuation causing painful efforts (before 2.08 vs after 1.07; P =.001) also decreased significantly. Conclusion PPR in patients with PPD significantly improves the symptoms of obstructive constipation, mainly with respect to mechanical assistance and difficult evacuation.

Resumen Introduccion La disinergia del piso pelviano (DPP) es una causa frecuente de estrenimiento por obstruccion defecatoria. El tratamiento de esta enfermedad esta basado en la rehabilitacion pelviperineal (RPP). El objetivo de este estudio es evaluar los resultados de la RPP en pacientes con DPP. Metodos Se incluye a pacientes con DPP a quienes se les realizo RPP entre el ano 2010 y el 2011. Se aplico previamente a las sesiones y al termino de ellas un cuestionario de estrenimiento (KESS) (escala de 0 a 39 puntos: a mayor puntuacion mayor sintomatologia). Se compararon los resultados del cuestionario KESS, de forma previa y posterior a la RPP. Analisis estadistico mediante Mann-Whitney-Wilcoxon para muestras pareadas; se considero significativo p Resultados Se incluyo a 13 pacientes (11 mujeres), edad promedio: 44,3 anos (r: 18-76). La puntuacion promedio del KESS previa y posterior al tratamiento fue de 19,6 (DE: 5,8) y de 12,6 puntos (DE: 6,3), respectivamente (p = 0,002). La frecuencia evacuatoria, consistencia de las deposiciones, dolor abdominal y distension abdominal no varian significativamente con el tratamiento. La necesidad del uso de enemas, laxantes o digitacion, asi como la evacuacion no exitosa o incompleta disminuyeron en forma significativa. Asimismo, el tiempo total de evacuacion (pre: 1,53 vs. post: 1; p = 0,012) y la percepcion de dificultad para evacuar (pre: 2,08 vs. post: 1,07; p = 0,001) mejoraron significativamente. Conclusiones La RPP en pacientes con DPP mejora significativamente los sintomas de la obstruccion defecatoria, principalmente con relacion a la asistencia mecanica y percepcion de dificultad defecatoria.

ResumenIntroducciónLa filtración de anastomosis es una de las complicaciones de mayor impacto en cirugía colorrectal.ObjetivoAnalizar la frecuencia e impacto de las filtraciones anastomóticas en cirugía laparoscópica colorrectal.Material y métodoEstudio longitudinal de base de datos prospectiva de pacientes operados por cirugía colorrectal entre julio de 2007 y agosto de 2014.ResultadosDe un total de 654 pacientes operados, 52,3% correspondían a hombres con una edad promedio de 57 años (42-72). La indicación más frecuente fue cáncer colorrectal con 244 pacientes, 159 (24,3%) operados por cáncer de colon y 85 (12,9%) por cáncer de recto, seguido por la enfermedad diverticular con 239 pacientes (36,5%) y 171 pacientes (26,1%) con otros diagnósticos. En 44 pacientes (6,7%) se objetivó filtración anastomótica, con una mediana de 4 días desde el postoperatorio para su diagnóstico. Como factores asociados a filtración se identificó al género masculino, riesgo anestesiológico según ASA, necesidad de conversión a laparotomía y la anastomosis ileoanal. En relación con el tratamiento, 15 pacientes (33,7%) fueron tratados de forma médica exitosa y 29 fue necesario reintervenirlos, de los cuales 23 (79,3%) requirieron una ostomía de protección. No hubo mortalidad asociada a la cirugía, y el promedio de hospitalización en los pacientes con filtración fue de 12 vs. 5 días para los pacientes sin filtración de la anastomosis.ConclusiónEste trabajo permite identificar a grupos de pacientes con mayor riesgo de filtraciones anastomóticas, quienes duplican su estadía hospitalaria y en un alto porcentaje deben ser reintervenidos. La sospecha y diagnostico precoz reducen la morbimortalidad.AbstractIntroductionAnastomotic leak is the most important complication on colorectal surgery.ObjectiveAnalyze the frequency and impact of anastomotic leaks in laparoscopic colorectal surgery.Material and methodsLongitudinal study of prospective database of patients undergoing colorectal surgery between July 2007 and August 2014.Results654 patients operated, 52.3% were men with an average age of 57 years (42-72). The most frequent indication was colorectal cancer in 244 patients, 159 (24.3%) operated for colon cancer and 85 (12.9%) for rectal cancer followed by diverticular disease in 239 patients (36.5%) and 171 patients (26.1%) with other diagnoses. In 44 patients (6.7%) anastomotic leakage was observed with a median of 4 days post surgery for diagnosis. As factors associated with filtration, we identified male gender, anesthesic risk according to ASA, need for conversion to laparotomy and ileoanal anastomosis. With regard to treatment, 15 (33.7%) were successfully treated with medical therapy alone and 29 required re-intervention, of which 23 (79.3%) required an ostomy protection. There was no mortality associated with surgery and average LOS was 12 vs. 5 days in patients with filtration compared with patients without anastomotic leakeage.ConclusionThis serie helps to identify patients groups with increased risk of anastomotic leakage who double their hospital LOS and in a higher percentage should need re-intervention. Suspicion and early diagnosis reduces morbidity and mortality.

Background: Selection of patients with Lynch Syndrome (LS) for a genetic study involves the application of clinical criteria. To increase the rate of identification of mutations, the use of molecular studies as Microsatellite Instability (MSI) and Im- munohistochemistry (IHC) in the tumor has been proposed. Aim: To demonstrate the usefulness of MSI and IHC in the detection of mutations in patients with LS. Material and Methods : From our Familial Colorectal Cancer Registry, families suspected of LS were selected according to Amsterdam or Bethesda clinical criteria. Screening of germline mutations of MLH1, MSH2 and MSH6 genes was performed. In addition, analysis of MSI and IHC were performed in colorectal tumors. Results : A total of 35 families were studied (19 met Amsterdam and 16 met Bethesda criteria). Twenty one families harbored a germline alteration in MLH1, MSH2 or MSH6 (18 Amsterdam and 3 Bethesda). In these families, eighteen different alterations were found, 15 of which were mutations and 3 corresponded to variants of uncertain pathogenicity. On the other hand, 80% of the tumors showed positive microsatellite instability (27 MSI-high and 1 MSI-low), and immunohistochemical testing showed that 77% of tumors had the loss of a protein. Correlation between results of tumor molecular studies and the finding of germline nucleotide change showed that IHC and MSI predicted mutations in 81 and 100% of patients, respectively. Conclusions : MSI and IHC can efficiently select patients with a high probability of carrying a mutation in DNA repair genes

El cáncer rectal se define como el tumor ubicado entre el margen anal y los 15 cm hacia proximal. En el cáncer de recto, una precisa estadificación preoperatoria permite clasificar correctamente a los pacientes para las diversas terapias existentes, así como seleccionar el mejor tratamiento quirúrgico. La estadificación preoperatoria se realiza con el apoyo de métodos imagenológicos. Dentro de los métodos actualmente disponibles están la endosonografía rectal (EUS), tomografía computada (TC), resonancia magnética (RM), tomografía por emisión de positrones (PET/CT) y ultrasonido intraoperatorio (IOUS). La EUS es un método realizado por el cirujano colorrectal, que permite la evaluación de la invasión de la pared, así como también de los linfonodos, sin embargo, su principal limitación es la evaluación del compromiso de la fascia mesorrectal. La RM es, hasta el momento, el mejor método para evaluar el compromiso de la fascia mesorrectal, además de informar el compromiso de pared y una adecuada evaluación de linfonodos comprometidos. La TC es un método ampliamente disponible, cuya principal utilidad es la evaluación de metástasis a distancia. El PET/CT está cobrando actualmente mayor importancia, sin embargo, su uso en estadificación preoperatoria aún no es ampliamente aceptado. La IOUS permite evaluar el compromiso metastásico del hígado durante la cirugía y por lo tanto, determina conducta y pronóstico. Por lo anterior, es necesario un conocimiento actualizado del cirujano en cuanto a esta metodología, sus ventajas y limitaciones.

In Chile, mortality from colorectal cancer (CRC) has increased rapidly. To help address this issue, the Prevention Project for Neoplasia of the Colon and Rectum (PRENEC) program was initiated in 2012 with intensive support from Tokyo Medical and Dental University (TMDU) in Tokyo, Japan, as part of an international collaboration.From June 2012 to July 2014, a total of 10,575 asymptomatic participants were enrolled in PRENEC. Participants with positive immunochemical fecal occult blood test (iFOBT) results or a family history of CRC underwent colonoscopy. The colonoscopy results from a similar, previous project in Chile (PREVICOLON) were compared with those from PRENEC. Furthermore, the initial colonoscopies of 1562 participants in PRENEC were analyzed according to whether the colonoscopists were from TMDU or Chile.The complete colonoscopy, adenoma detection, and cancer detection rates were 88.0%, 26.7%, and 1.1%, respectively, in PREVICOLON, while the corresponding values were 94.4%, 41.8%, and 6.0%, respectively, in PRENEC. In PRENEC, 107 cases of CRC were detected, amounting for 1.0% of all participants. Considering initial colonoscopies in PRENEC, the complete colonoscopy, adenoma detection, and cancer detection rates were 97.4%, 45.3%, and 9.3%, respectively, for physicians at TMDU and 93.3%, 41.5%, and 5.1%, respectively for Chilean physicians. The detection rates of intramucosal cancer were 7.3% and 3.7%, respectively, for TMDU and Chilean physicians.Quality indicators of colonoscopy substantially improved from PREVICOLON to PRENEC. The assessments made by Chilean physicians alone were improved in PRENEC, but remained better in the TMDU group. Moreover, physicians from TMDU detected more CRCs than Chilean physicians, especially at earlier stages.

Introducción: En el cáncer colorrectal (CCR), se sugiere que un mejor pronóstico podría asociarse a una respuesta inmune antitumoral (del huésped) y/o a la presencia de una alta inestabilidad microsatelital (MSI). Objetivo: Determinar si los niveles de expresión de los marcadores de linfocitos T (CD3/CD4/CD8/ CD45RO/FoxP3) y el estado de MSI se asocian a estadios metastásicos en pacientes con CCR. Material y Método: Estudio prospectivo de 109 pacientes con diagnóstico de CCR. El análisis de expresión de los marcadores CD3/CD4/CD8/CD45RO/FoxP3 fue realizado por inmunohistoquímica; los tumores fueron clasificados en negativo, débil e intenso. La MSI fue evaluada con siete marcadores amplificados desde ADN normal y tumoral; los tumores fueron agrupados en: MSS (estable)/MSI-baja y MSI-alta. El análisis estadístico fue realizado con el test exacto de Fischer. Resultados: Una intensa expresión de los marcadores CD3+, CD4+, CD8+ y CD45RO+, fue observada en el 29%, 28%, 12% y 86% de los tumores, respectivamente. El 16% de los tumores presentó MSI-alta. Los tumores que presentan una alta densidad de linfocitos T (CD3+, CD4+ y CD45RO+) se asocian a estadios tempranos I-II (p = 0,023; p = 0,030 y p = 0,003, respectivamente). Adicionalmente, se identificó una asociación estadística significativa entre los tumores con MSS/MSI-baja y una menor capacidad de reclutar linfocitos T citotóxicos CD8+ (p = 0,037) y totales CD3+ (p = 0,064). Conclusión: Existe una asociación entre altas densidades de linfocitos T CD3+, CD4+ y CD45RO+ y tumores con estadios no metastásicos. Además, tumores con MSS/MSI-baja se asocian a un menor reclutamiento de linfocitos T CD8+ y CD3+.

Colorectal cancer is a multistep process affecting several signaling pathways including EGFR (epidermal growth factor receptor), a therapeutic target for metastatic disease. Our aim was to characterize the mutational and expression profiles of the EGFR pathway in colorectal tumors and to integrate these results according to five previously defined groups. We screened seven genes for mutations ( KRAS-BRAF-PIK3CA-PIK3R1-AKT1-MAP2K1-PTEN) and six proteins (EGFR-p110α-p85α-PTEN-phosphoAKT-phosphoMEK1) by immunohistochemistry, PTEN deletion, and MSI. At least one mutated gene was observed in 68% of tumors ( KRAS 45%, PIK3CA 21%, BRAF 14%, and PTEN 7%). PTEN deletion was observed in 10.7% of tumors and 19.6% were MSI-High. In all, 54% of tumors showed a high EGFR expression, 48% p110α, 4.4% phosphoAKT, and 22% phosphoMEK1; and 43% showed low PTEN expression and 22% p85α. In total, five groups of tumors were defined based on MSI, BRAF, and KRAS mutations. Three groups gather mainly early-stage tumors, whereas a fourth group is mostly conformed by advanced tumors. We described here that 71.4% of tumors from one group have a mutated PI3K/PTEN pathway, in comparison to other groups having 32%, 27%, and 25%. In addition, the five groups are differentiated by molecular features such as EGFR, p85α, p110α, and PTEN, showing variable expression among tumor groups. In conclusion, alterations on the EGFR pathway were found in a high percentage of colorectal cancer patients. Using the integration of diverse molecular markers, we ratified previous classification in an ethnic group having relevant genetic differences and living in a different environmental background, adding complementary molecular targets related to therapy.

In Chile, colorectal cancer (CRC) is often diagnosed in late stages. Thus, surgical treatment must be complemented with chemotherapy. KRAS mutations and microsatellite instability have been detected in these tumors. However, the response to treatment in patients without KRAS mutations varies and requires a better understanding.To determine the frequency and distribution of somatic point mutations in KRAS, BRAF and PIK3CA genes and microsatellite instability status (MSI) in patients with colon cancer (CC).A prospective observational study of patients undergoing surgery for colon cancer. Tumor-derived DNA was analyzed by polymerase chain reaction (PCR) for the most frequent mutations of KRAS, BRAF and PIK3CA. PCR was also used to analyze MSI.Fifty-eight patients with sporadic CC were analyzed, 16 showed KRAS mutations (G12R, G12D, G12V, G13D) and out of the 42 patients that did not show any mutation, 10 had mutations in BRAF (V600E) and PIK3CA (E542K, E545D, E545K, Q546E, H1047R). BRAF mutations alone or in combination with PIK3CA mutations were observed in 27% of high MSI tumors and in 2% of tumors without instability (p0.049). A higher percentage of high MSI tumors were located in the right colon (p0.001), and showed BRAF mutation (p0.020).The highest percentage of high MSI and BRAF mutations was observed in the right colon. Therefore, this study suggests the presence of different molecular features between right and left colon tumors that should be considered when defining the therapeutic management.

The molecular testing of KRAS mutation status in metastatic colorectal cancer patients is mandatory to identify patients eligible for anti-epidermal growth factor receptor monoclonal antibody therapy.To report the frequency of KRAS gene mutations in Chilean patients with colorectal cancer (CRC).A cohort of 262 Chilean patients with CRC aged 26 to 90 years (53% males), was studied. KRAS mutation status was analyzed by real-time polymerase chain reaction and correlated with clinicopathological data.Ninety-eight patients (37%) were positive for KRAS mutations. G12D was the most common mutation with a frequency of 36.7%, followed by G12V (25.5%), G13D (17.3%), G12A (7.1%), G12C (6.1%), G12S (5.1%) and G12R (2%). The frequency of the mutation in left, right colon and rectal tumors was 37.8, 32.6 and 44.9%, respectively. Among tumors with mutations, 86.7% were well or moderately differentiated tumors and the rest were poorly differentiated. No significant associations between KRAS gene mutations and other clinicopathological features of the tumor were observed.The frequencies of KRAS mutations reported in this study are similar to frequencies reported for European and North-American populations, lower than in a Spanish study and higher than in a Peruvian study.

The incidence and prevalence of Inflammatory Bowel Disease (IBD) has increased.To determine demographic and clinical characteristics of patients with IBD in a Chilean private hospital.Review of a prospective registry of patients with IBD, started on 2012. It includes clinical, imaging, endoscopical and pathological information of patients.Data of 316 patients with IBD, aged 16 to 86 years (56% females), were analyzed. Ulcerative Colitis (UC), Crohn´s and non-classifiable IBD were diagnosed in 230, 77 and 9 patients, respectively. The disease was diagnosed in 82% of patients in the period between 2002 and 2012. There was a peak in the diagnosis of both UC and CD between 20 and 39 years of age, without gender differences. The disease switched from UC to CD in six patients. In four, there was a change in disease behavior. Thirty eight patients were treated with biological therapy. The median lapse between the diagnosis and the use of biological therapy was 1 year in patients diagnosed after 2007, compared with 5.5 years among those patients diagnosed before 2007 (p = 0.001). There was a trend towards a higher requirement of surgery until 2006. Subsequently there was a stabilization of the requirement, concomitant with the incorporation of biological therapy.An adequate registry of IBD patients is necessary to improve demographic and clinical characteristics. A national registry is needed to assess the epidemiological changes of IBD in Chile.

Crohn’s disease (CD) is a multifactorial pathology associated with the presence of adherent-invasive Escherichia coli (AIEC) and NLRP3 polymorphic variants. The presence of intracellular E. coli in other intestinal pathologies (OIP) and the role of NLRP3-inflammasome in the immune response activated by these bacteria have not been investigated. In this study, we sought to characterize intracellular strains isolated from patients with CD, ulcerative colitis (UC) and OIP, and analyze NLRP3-inflammasome role in the immune response and bactericidal activity induced in macrophages exposed to invasive bacteria. For this, intracellular E. coli isolation from ileal biopsies, using gentamicin-protection assay, revealed a prevalence and CFU/biopsy of E. coli higher in biopsies from CD, UC and OIP patients than in controls. To characterization of bacterial isolates, pulsed-field gel electrophoresis (PFGE) patterns, virulence genes, serogroup and phylogenetic group were analyzed. We found out that bacteria isolated from a given patient were closely related and shared virulence factors; however, strains from different patients were genetically heterogeneous. AIEC characteristics in isolated strains, such as invasive and replicative properties, were assessed in epithelial cells and macrophages, respectively. Some strains from CD and UC demonstrated AIEC properties, but not strains from OIP. Furthermore, the role of NLRP3 in pro-inflammatory cytokines production and bacterial elimination was determined in macrophages. E. coli strains induced IL-1β through NLRP3-dependent mechanism; however, their elimination by macrophages was independent of NLRP3. Invasiveness of intracellular E. coli strains into the intestinal mucosa and IL-1β production may contribute to CD and UC pathogenesis.