Programa multicéntrico de cribado de cáncer colorrectal en Chile / Results of a multicentric colorectal cancer screening program in Chile

Background: Colorectal Cancer Screening Programs (CRCSP) are widely accepted in developed countries. Unfortunately, financial restrictions, low adherence rate and variability on colonoscopy standardization hamper the implementation 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 cardiovascular 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.

Impacto de las filtraciones anastomóticas en cirugía colorrectal / Impact of anastomotic leak in colorectal surgery

Introducción: La filtración de anastomosis es una de las complicaciones de mayor impacto en cirugía colorrectal. Objetivo: Analizar la frecuencia e impacto de las filtraciones anastomóticas en cirugía laparoscópica colorrectal. Material y método: Estudio longitudinal de base de datos prospectiva de pacientes operados por cirugía colorrectal entre julio de 2007 y agosto de 2014. Resultados: De 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. Conclusión: Este 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.

Introduction: Anastomotic leak is the most important complication on colorectal surgery. Objective: Analyze the frequency and impact of anastomotic leaks in laparoscopic colorectal surgery. Material and methods: Longitudinal study of prospective database of patients undergoing colorectal surgery between July 2007 and August 2014. Results: 654 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. Conclusion: This 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.

Se justifica el seguimiento después de una colectomía en pacientes con poliposis adenomatosa familiar / The follow up after colectomy in patients with familial adenomatous polyposis is justified

phenotypic expression is the presence of múltiple colorectal adenomatous polyps (more than 100), with high probability developing colorrectal cancer (CRC) before the fifth decade of life. Prophylactic surgery (total colectomy or restorative proctocolectomy) reduces the risk of developing CRC. However, the risk of developing tumors in other organs remains present. Objetive: Analyze the frequency and type of tumors associated with classic familial adenomatous polyposis syndrome (FAPc) patients undergoing prophylactic colectomy. Material and Methods: Cohort study. From the registry of hereditary colorrectal cancer (CRC) at our institution, we identified patients with FAPc who underwent total colectomy with ileorrectal anastomosis (TC-IRA) or restorative proctocolectomy (RTPC), from 1999 to 2014. In the follow-up we analyzed related tumors and mortality. Results: 27 patients, of whom 18 (66.7%) underwent TC-IRA and 9 (33.3%) underwent RTPC. At the time of surgery, 4 patients had CRC (15%) and 5 had extracolonic tumors (osteomas). In a mean follow-up of 49, 4 months (i: 2 y 178) the following lesions were diagnosed: digestive tract adenomas in 17 (63%) patients, of these 2 required a proctectomy and 3 resection of duodenal adenomas. Eight patients developed desmoid tumors (30%), and 3 of them underwent surgery. One patient had an extradigestive tumor (thyroid cancer) and only 8/27 (29.6%) did not develop other tumors. One patient died due to progression of his CCR. Discussion: In this series it is confirmed that most patients will develop neoplasms FAPc after colectomy. conclusion: The removal of the colon and/or rectum is able to prevent the development of CRC. However, two thirds of the patients develop other tumors in which systematic surveillance allowed early detection and treatment.

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.

Análisis molecular del cáncer de colon esporádico / Molecular analysis of sporadic colon cancer

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.

Impacto de un programa de nivelación de ciencias básicas en estudiantes de primer año de la carrera de Medicina / Effects on academic performance of a leveling program in basic sciences in first year medical students

Background: A significant number of students in health careers do not have the knowledge to approve basic courses. Therefore, educational programs to level off knowledge have been developed. Aim: To associate the results of a leveling program with the academic performance in cell biology (CB) and biochemistry (BC) of first year medical students. Material and Methods: We applied a test to first year medical students at the beginning and end of the leveling program (control test). The results obtained at the end of the leveling program were correlated with the results obtained in CB and BC. Results: Fifty seven of89 (64%) first year medical students met the study entry criteria (54% female). Students who completed the leveling program had a significantly higher approval rate in CB (93% versus 75%, P = 0.024), and in BC (95% versus 69%, P = 0.001). After completing the leveling program, the risk of failing CB and BC, decreased by 72 and 84% respectively Conclusions: This study shows that medical students who participate in the leveling program decrease the chances of failing in CB and BC.

Síndrome de Lynch: selección de pacientes para el estudio genético mediante análisis de inestabilidad microsatelital e inmunohistoquímica / Lynch syndrome: selection of families by microsatellite instability and immunohistochemistry

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.

Caracterización clínica y genética de las poliposis intestinales hereditarias / Clinics and genetic characteristics in hereditary colon polyposis

Se denomina pólipo intestinal a una lesión visible elevada o tumor que se proyecta desde la superficie epitelial al lumen visceral. En relación al número, presencia de antecedentes familiares, manifestaciones extraintestinales y estudios genéticos es que se constituyen diversas poliposis intestinales. Si bien, las poliposis intestinales se manifiestan en general en la edad adulta, existen manifestaciones que pueden hacer sospechar la presencia de un síndrome poliposico hereditario en la infancia. Además en una proporción considerable estas poliposis presentan manifestaciones extraintestinales, tanto benignas como tumores en otros órganos. Es por esto, que una alta tasa de sospecha, en particular frente a pacientes con antecedentes familiares, puede conducir a un diagnóstico y tratamiento oportuno, además de considerar a la familia como potenciales pacientes e ingresar al grupo familiar a un registro de tumores hereditarios. Diversas técnicas de biología molecular han permitido la identificación de las mutaciones que son heredadas en estas enfermedades, permitiendo realizar conductas preventivas al saber el riesgo de cada persona en una familia afectada. El objetivo de esta revisión, es caracterizar las distintas poliposis intestinales, en cuanto a sus manifestaciones clínicas, clasificaciones, estudio genético y enfrentamiento multidisciplinario.

Polyps are solid or tumoral elevated lesions that arise from the intestinal epithelium so that they become visible in the intestinal epithelium so that they become visible in the intestinal lumen. Information regarding familial history, number, extraintestinal manifestations and genetic studies of polyps, assemble different types of intestinal polyposis. Generally, clinical manifestations occur in adult patients, although in children there are several signs that should make the physician suspect a hereditary polyposis syndrome. In addition it is important to know extraintestinal manifestations which are mostly benign but tumors may be present in other organs too. Bearing in mind that high clínical suspicion of hereditary polyposis syndrome especially if familial history is present, provides early diagnosis and appropriate treatment for the patient and eventually for the family members that could be affected, entering that family in a registry of hereditary tumors. Molecular biology has created different techniques to identify the presence of hereditary mutations that are specific for intestinal polyposis. Acknowledgment of these mutations establishes risks groups allowing adequate prevention strategies. The objective of this revision is to characterize and different types of intestinal polyposis, according to clinical manifestations, classification, genetic study and multidisciplinary approach.

Programa de detección de neoplasias colorrectales en población mayor de 50 años / A screening program for colorectal cancer in Chilean subjects aged fifty years or more

Background: Mortality from colorectal cancer (CCR) in Chile has nearly doubled over the past 15 years. International studies have shown that CCR screening programs based on fecal occult blood test (FOBT) reduce CCR mortality. Aim: To analyze the results from a CCR screening model in people over 50 years. Material and Methods: Between 2007 and 2009, a prospective multicenter study was performed in seven major Chilean cities. FOBT using an immunological method, was measured in asymptomatic subjects aged 50 years or more, without risk factors. In patients with a positive FOBT, with symptoms or with family risk factors, a colonoscopy was indicated. Results: A total of 6348 subjects were assessed, FOBT was performed in 4938 of them, with a compliance of 77%. The result was positive in 9.6%. A total of 2359 colonoscopies were ordered, with an overall compliance of 50.1%. Of the 1184 colonoscopies performed, adenomas and high risk adenomas were found in 304 (26%) and 75 (6%) patients, respectively. Thirteen patients were diagnosed with stage I and IICCR. Three of these lesions were excised endoscopically and 10 surgically. The detection rate of polyps, high risk adenomas and cancer was 75, 12 and 2 per 1000 screened individuals, respectively. Conclusions: This program allowed the early detection of an important number of high risk colon lesions, and all patients with CCR were diagnosed at early stages.

Prevalencia de la incontinencia fecal en centros de salud y casas de reposo / Prevalence of fecal incontinence in health centers and nursing home residents

Background: Fecal and urinary incontinence (FI and UI) are psychologically and socially debilitating and embarrassing conditions. Aim: To determine the prevalence of FI and associated factors in patients assessed in health centers (HC) and nursing home (NH) residents. Material and Methods: Prospective, multicentric survey carried out in 3 HC and 16 NH of Santiago. Patients and residents of NH were interrogated about FI between March and July 2004. Results: The questionnaire was answered by 618 patients attending health centers aged 18 to 87 years (75 percent females) and 128 nursing home residents aged 40 to 103 years (80 percent females). The prevalence of liquid or solid FI in HC and NH was 2.7 and 45 percent, respectively. Among the latter, the incontinence for liquids and solids was 19 percent and 42 percent, respectively. The prevalence of UI was 30.1 and 62.7 percent in HC patients and NH residents, respectively. Among patients attending HC, multivariable analysis showed a relation between older age and urinary incontinence with liquid or solid FI Among NH residents, multivariate analysis showed a relation between urinary incontinence and motor disabilities with liquid or solid FI Conclusions: The prevalence of liquid or solid FI among patients assessed in health center is 2.7 percent. This figure increases in older people, those with UI and in NH residents.