Pablo uzmán G
University of La Frontera
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Featured researches published by Pablo uzmán G.
Revista Medica De Chile | 2001
Iván Roa E; Xabier de Aretxabala U; Juan C Araya O; Miguel Villaseca H; Juan Carlos Roa S; Pablo Guzmán G
Background: There is little information about the behavior of early gallbladder carcinoma. Aim: To report the clinical and pathological features of 196 patients with early gallbladder carcinoma. Material and methods: All patients with gallbladder cancer diagnosed between 1988 and 1997 were reviewed. In 703 of 829 patients, there was information about clinical features and follow up, and were included in this study. All gallbladders were subjected to a complete mapping. When neoplastic cells involved only the mucosa or muscular layer, the tumors were considered as early. Results: One hundred ninety six patients had an early carcinoma (161 women, aged 57.5 years and 35 male, aged 63.4 years). One hundred twenty eight tumors were located in the mucosa and 68 in the muscular layer. Patients with tumors involving the mucosa were younger than those with tumors involving the muscular layer. All tumors were adenocarcinomas, 66% were well differentiated and 32% moderately differentiated. Tumors were not visible macroscopically in 132 cases. Five and 10 years survival was 92%. Subjects of less than 40 years old had a 100% survival at 5 years. A hepatic and lymph node resection was done in 12 patients with tumors infiltrating the muscular layer but in only one, the tumor infiltrated the liver. No difference in survival was observed when a simple cholecystectomy or radical surgery was done. Conclusions: Nearly 25% of gallbladder carcinomas can be classified as early and its diagnosis requires a directed study
Revista Medica De Chile | 2004
Juan Carlos Roa S; Leonardo Anabalón R; Oscar Tapia E; Javier Martínez S; Juan Carlos Araya O; Miguel Villaseca H; Pablo Guzmán G; Iván Roa E
: We found methylation inat least one of the genes studied in 88% of cases and in 3 or more genes in 40.5% of cases. Thefrequencies of promoter hypermethylation of CDKN2A, hMLH1, APC, CDH1 and FHIT were41.4%, 11.4%, 52.9%, 70% y 42.9%, respectively. We found a relationship between CDKN2A me-thylation and better survival (p=0.002). CDH1 methylation and poor histological differentiation(p=0.007), hMLH1 methylation and non-Mapuche ethnicity (p=0.03), APC methylation and larg-er tumor size (p <0.05), FHIT methylation and lack of estrogen receptor IHC expression (p <0.05).
Revista Medica De Chile | 2007
Susana Aedo A; Angélica Melo A; Patricia García; Pablo Guzmán G; Italo Capurro V; Juan Carlos Roa S
. Los genotiposde HPV que infectan el tracto genital femenino, sehan clasificado en 2 grupos: de bajo riesgo (BR) y dealto riesgo (AR) segun el potencial oncogenico parael desarrollo de lesiones preneoplasicas o neoplasi-cas. Los genotipos de bajo riesgo (BR) mas frecuen-tes son los HPV: 6, 11, 43 y 44 y se asocian concondilomas o neoplasias cervicales intraepitelialesde bajo grado (LBG). En el grupo de alto riesgo (AR)15 tipos de HPV han sido identificados (HPV 16, 18,31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73 y 82),detectados principalmente en neoplasia cervicalintraepitelial de alto grado (LAG) y carcinomas
Revista Medica De Chile | 2004
Juan Carlos Roa S; Quynh N. Vo; Juan Carlos Araya O; Miguel Villaseca H; Pablo Guzmán G; Gilda Ibacache S; Xabier de Aretxabala U; Iván Roa E
: We analyzed themethylation status of the promoter region of the CDKN2A gene in gallbladder adenocarcinomasusing methylation specific PCR (MSP). We also used microsatellite markers near the CDKN2Agene to detect allelic imbalance (AI) and examined the tumors by immunohistochemistry (IHC)for p16 expression.
Revista Medica De Chile | 2002
Iván Roa E; Xabier de Aretxabala U; Juan Carlos Roa S; Juan C Araya O; Miguel Villaseca H; Pablo Guzmán G; Luis Burgos S
Gallbladder cancer is frequent in Chile, but it is not uniformly mortal. The diagnosis is usually made after a cholecystectomy. indicated for a symptomatic cholelithiasis. Global survival of gallbladder cancer can be as high as 40% at five years. In 69% of women of less than 30 years old, the tumor is detected in early stages. In these cases, cholecystectomy is the curative procedure, with a 90% survival at five years. According to our experience, cholecystectomies should be performed between 40 and 50 years of age in men and between 30 and 40 years in women. The prognostic factors that should be considered are symptoms associated to lithiasis, age, parity, obesity, size of stones and the size of the gallbladder. If the tumor is detected in early stages, the survival is good. The natural history of the disease would change significantly if all women with symptomatic stones were operated (Rev Med Chile 2002; 130: 1295-1302).
Revista Medica De Chile | 2008
Juan Carlos Roa S; Patricia García M; Angélica Melo A; Oscar Tapia E; Miguel Villaseca H; Juan Carlos Araya O; Pablo Guzmán G
Background: The loss of tumor suppresor gene function damages the defensive mechanisms that protect the indemnity of genetic material. Promoter gene methylation is one of the inactivation mechanisms of suppressor genes. Aim: To study the methylation pattern of a group of genes in biopsy samples of gastrointestinal tumors. Material and methods: Forty eight gastric, 25 gallbladder, 24 colon and 6 pancreas cancer biopsy samples were randomly selected. The methylation pattern of CDH1, FHIT, CDKN2A, APC and MLH1 genes, was studied using a specific polymerase chain reaction test for methylation. Demographic, morphological and follow up variables of patients bearing the tumors were also analyzed. Results: The general methylation frequency of CDH1, FHIT, CDKN2A, APC and MLH1 genes was 64.1, 56, 39.8, 18.1 and 34% respectively. In gastric cancer samples there was a correlation between APC gene methylation and well differentiated tumors; between CDH1 methylation and Lauren diffuse type and the presence of three or more metastasic lymph nodes; between FHIT, CDKN2A and CDH1 gene methylation and male gender. In iess differentiated gallbladder tumors, the frequency of CDH1 methylation was higher. There was a tendency towards a lower survival in colon and gastric cancer when MLH1 (p =0.07) y CDKN2A (p= 0.06) were methylated, respectively. Conclusions: An abnormal methylation pattern was associated with morphological features in gastric and gallbladder cancer and with a tendency towards a lower survival in colon and gastric cancer
Revista Medica De Chile | 2006
Pablo Guzmán G; Juan Araya O; Miguel Villaseca H; Iván Roa E; Angélica Melo A; Sergio Muñoz N; Juan Carlos Roa S
l cancer gastrico es la segunda neoplasia masfrecuente a nivel mundial, despues del cancerpulmonar. Las mayores incidencias se registran enChina, Japon, Europa del Este y Sudamerica. Estaneoplasia ocupa el segundo lugar a nivel mundialen mortalidad, con mejor sobrevida solo en Japon,Australia y Nueva Zelanda, debido principalmenteal diagnostico precoz
Revista Medica De Chile | 2010
Jaime López M; Carmen Gloria Ili G; Priscilla Brebi M; Patricia García M; Italo Capurro V; Pablo Guzmán G; Eugenio Suárez P; José Manuel Ojeda F; Juan Carlos Roa S
The relationship between human papillomavirus (HPV) and uterine cervical cancer (UCC) is widely known and accepted. Aim: To determine the frequency of genotypes of HPV in cervical preneoplastic lesions in a high risk area of UCC. Material and Methods: Using a combination of PCR and Reverse Line Blot technique, 235 formalin fixed paraffin embedded samples, with diagnosis of low-grade squamous intraepithelial lesion (LSIL) or high-grade squamous intraepithelial lesion (HSIL) were genotyped. Results: HPV was detected in 61.2% of LSIL and 78.1% of HSIL. The main genotypes found were HPV 16, 18, 31, 45, 56 y 58. HPV 16 was the most common in both LSIL (18.1%) and HSIL (36.9%). HPV 16 or 18 were present in 25.1% and 47.1% of the LSIL and HSIL respectively. In both LSIL and HSIL, the predominant viral genotypes were those types classified as with a high oncogenic risk. Conclusions: HPV genotypes 16, 18, 31, 45, 56 y 58 were the most common in our series. HPV 16 and 18, viral types with high oncogenic risk and included in commercial vaccines, were found in 25.1% and 47.1% of LSIL and HSIL, respectively.
Revista Medica De Chile | 2002
Iván Roa E; Gilda Ibacache S; Angélica Melo A; Erick Morales M; Miguel Villaseca H; Juan Araya O; Juan Carlos Roa S; Pablo Guzmán G; Xabier de Aretxabala U
Background: Subserous gallbladder carcinoma is difficult to diagnose and treat. There are no tissue markers with prognostic value in this type of tumor. Aim: To study the immunohistochemical expression of E-cadherin alpha and beta catenin in subserous gallbladder carcinoma. Patients and methods: One hundred seventeen subjects (103 women and 14 men aged 62 and 69 years as a mean, respectively), were studied. Thirty five gallbladder samples without evidence of cancer were used as controls. Expression of markers was studied with standard immunohistochemical techniques for formalin fixed and paraffin embedded tissue. Results: Ninety seven percent of tumors were adenocarcinoma. A lower or absent expression of E-cadherin, alpha catenin and beta catenin was observed in 26, 33 and 29% of tumors, respectively. Actuarial five years survival was 37%. No association between macroscopic features of the tumor and survival was observed. Well differentiated tumors had a 73% survival, whereas less differentiated tumors had a 30% survival. Tumors with a normal expression of the markers had a slightly better survival, although not significant (p=0.06). Conclusions: Approximately 30% of subserous gallbladder carcinoma have an abnormal expression of E-cadherin, alpha catenin and beta catenin. This abnormal expression has no relationship with prognosis and is probably secondary to the aberrant genic expression of the tumor (Rev Med Chile 2002; 130: 1349-57)
Revista Chilena De Cirugia | 2011
Pablo Guzmán G; Miguel Villaseca H; Lilia Antonio P; Juan Araya O; Paola Aravena M; Carla Cravero P; Pilar Pino M; Juan Carlos Roa S
Oral and oropharingeal squamous cells carcinoma. Clinico-pathological study Introduction: Oral cancer is a common disease in many parts of the world, in Chile only accounts for 1.6% of all cancers. The majority is squamous cell carcinoma with important clinical, epidemiological and pathological differences between lip, oral and orofaringeal locations. Objective: To analyze clinical and pathological characteristics of oral and oropharingeal squamous cell carcinoma in Temuco, Chile. Materials and Methods: A descriptive, retrospective study of all diagnosed cases in 15 years (1994 and 2008). The patients were analyzed according to gender, age; and the tumors were classifi ed based on anatomic location, size, macroscopical fi ndings and degree of differentiation. Results: We found 93 carcinomas, with male to female ratio of 5:1, average age 67 years. Patients under 50 years accounted for only 8% of cases. The most common sites were lower lip, tongue and gingiva, with an average size of 28 mm, which increased towards orofarinx and more than half were moderately differentiated. Conclusions: In our region, this carcinoma most often affects the seventh decade of life and male population and has similar characteristics to those in other countries which is predominantly. The size at diagnosis is signifi cant. The detection of some differences in the group with mapuche surnames warrants a study with a larger number of cases.