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Biomedical subjects

Juan Carlos Roa

Publications and source records attributed to Juan Carlos Roa.

At least 19 recordsLinked to original sources

Chemoradiotherapy in gallbladder cancer.

Gallbladder cancer (GC) is considered a rare disease associated with a poor prognosis. Unfortunately, the low number of cases makes the performance of trials addressing the role of adjuvant, neoadjuvant, and/or palliative therapy difficult. For a long time, the majority of trials were 5-fluorouracil (5 FU)-based, and results were uniformly poor. Since the introduction of Gemcitabine, response rates of approximately 30% have been observed through the use of this drug and new approaches have been tested. In this sense, drugs such as Cisplatin and Capecitabine have been employed concurrently with gemcitabine and/or radiation. Since a recurrence pattern is both distant and local, chernoradiation seems a logical option to deal with the disease. However, at the present time, the lack of valid and scientific evidence means that most of the recommendations originate from trials dealing with other tumors, such as pancreas cancer and biliary tract cancer (BTC). The aforementioned treatment alternatives warrant further evaluation focusing on GC.

Antimetabolites, Antineoplastic↗

[Frequency of K-ras mutation in biliary and pancreatic tumors].

BACKGROUND: The ras gene family (H-ras, N-ras and K-ras) are oncogenes that mutate frequently in human cancer, specially in tumors of the biliary tract and pancreas. AIM: To determine the frequency of K-ras gene codon 12 mutation in pancreatic and biliary tumors. MATERIAL AND METHODS: Samples of 35 gallbladder, 15 ampulla of Vater, 10 biliary tract and 9 pancreatic tumors, were analyzed. The tumor tissue was microdissected from paraffin embedded biopsies. The mutation was detected by a combination of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). RESULTS: Overall, 46% of samples had K-ras gene mutations. Mutation frequency was 80, 56, 50 and 29% for ampulla of Vater, pancreatic, biliary tract and gallbladder tumors, respectively. When compared with the rest, gallbladder tumors had a significantly lower frequency of the mutation. Median survival for biliary tract tumors was 6 months, compared with 65 months for gallbladder tumors (p <0.05). CONCLUSIONS: Gallbladder carcinoma had the lower frequency of K-ras mutation, when compared with pancreatic, biliary tract and ampulla of Vater tumors.

Adult↗

Promoter methylation profile in gallbladder cancer.

BACKGROUND: Methylation in the promoter region of genes is an important mechanism of inactivation of tumor suppressor genes. Our objective was to analyze the methylation pattern of some of the genes involved in carcinogenesis of the gallbladder, examining the immunohistochemical expression of proteins, clinical features, and patient survival time. METHODS: Twenty cases of gallbladder cancer were selected from the frozen tumor bank. The DNA extracted was analyzed by means of a methylation-specific polymerase chain reaction test for the CDKN2A (p16), MLH1, APC, FHIT, and CDH1 (E-cadherin) genes. Morphological and clinical data and follow-up information were obtained. RESULTS: All cases were in an advanced stage: histologically moderate or poorly differentiated tumors (95%). Methylation of the promoter area of genes was observed in 5%, 20%, 30%, 40%, and 65% of cases, and an altered immunohistochemical pattern (AIP) in 5%, 35%, 21%, 25%, and 66% for the MLH1, CDKN2A, FHIT, APC, and CDH1 genes, respectively. The Kappa concordance index between methylation of the promoter area and AIP for the MLH1 and CDH1 genes was very high (K > 0.75) and substantial for APC (K > 0.45). No correlation was found between survival time and the methylation of the genes studied. CONCLUSIONS: The high frequency of gene methylation (with the exception of MLH1) and the high agreement between AIP and methylation of the gene promoter area for the MLH1, APC, and CDH1 genes suggest that the inactivation of tumor suppressor genes and of the genes related to the control of cellular proliferation through this mechanism is involved in gallbladder carcinogenesis.

Acid Anhydride Hydrolases↗

Gallbladder cancer: an analysis of a series of 139 patients with invasion restricted to the subserosal layer.

The goal was to study our experience in the management of a series of patients with a potentially curative subserosal gallbladder cancer who were prospectively treated by the authors. Between April 1988 and July 2004, 139 patients were enrolled in our prospective database. Of the above, 120 were operated on with an open procedure and the rest with laparoscopic surgery. In only eight patients was the diagnosis suspected before the cholecystectomy. The majority of tumors were adenocarcinoma. Six patients had an epidermoid tumor, and one had a carcinosarcoma. Of the patients, 74 underwent reoperation, while in 55 (70.2%) it was possible to perform an extended cholecystectomy with a curative aim. Operative mortality was 0%, and operative morbidity was 16%. Lymph node metastases were found in 10 (18.8%), while in 7 (13.2%) the liver was involved. The overall survival rate was 67.7%, while in those who underwent resection, the survival rate was 77%. Through the use of a multivariate analysis, the presence of lymph node metastasis was found to be an independent factor with respect to prognosis. The feasibility of performing an extended cholecystectomy in patients with gallbladder cancer and invasion of the subserosal layer allows for a good survival rate. The presence of lymph node metastases represents the main poor prognosis factor, and some type of adjuvant therapy should be studied in this particular group.

Adenocarcinoma↗

Prognostic factors of phyllodes tumor of the breast.

The phyllodes tumor is characterized by its tendency to recur locally and occasionally to metastasize. The purpose of the present paper was to assess the prognostic value of clinical-morphological characteristics in patients with phyllodes tumor. Forty-seven cases of phyllodes tumors was studied; the World Health Organization classification was used and follow up was obtained. A total of 51%, 28% and 21% of the tumors were classified as benign, borderline and malignant, respectively. The adherence (P = 0.01), size >10 cm (P = 0.001), high mitotic activity (P = 0.03), infiltrative tumor margin (P = 0.0002) and type of surgery in malignant tumors (P = 0.02) proved to be good predictors of relapse. The presence of pain (P = 0.03), postmenopausal status (P < 0.04), heavy cellular pleomorphism (P = 0.007), high mitotic activity (P = 0.002), tumoral grade (P = 0.006) and metastasis (P < 0.00001) were prognostic factors of poor survival. Tumoral grade and some clinical-morphological characteristics of patients with phyllodes tumors have a significant impact on the prediction of its biological behavior.

Adult↗

[Promoter methylation profile in gastric cancer].

BACKGROUND: Promoter genomic DNA methylation is an important inactivation mechanism of tumor suppressor genes. This genetic-molecular pathway for cancer may separate a subset of patients with different prognoses and eventually different responses to specific therapies. AIM: To analyze the methylation pattern of important genes related to different carcinogenic mechanisms in patients with gastric cancer (GC) and the relationship with its morphological features and biological behavior. MATERIAL AND METHODS: Forty-seven fresh-frozen GC samples were selected. The methylation-specific PCR (MSP) test was used to analyze promoter methylation status for genes MLH1, CDKN2A (p16), APC, CDH1 (Cadherin E) and FHIT. Follow-up and complete morphological features were obtained for all cases. RESULTS: We found methylation in at least one of the genes studied in 83% of the cases. The frequencies of promoter hypermethylation of MLH1, CDKN2A, APC, CDH1 and FHIT were 31%, 43%, 46%, 80% y 62%, respectively. We found a relationship between APC methylation and good histological differentiation (p =0.03); CDH1 methylation with diffuse type by Lauren and 3 or more metastasic lymph nodes (p <0.05); FHIT, CDKN2A and CDH1 methylation and female condition (p <0.04). We also found a non-significant relationship between CDKN2A methylation and better survival (p =0.07). CONCLUSIONS: The high frequency promoter methylation found confirms its importance in gastric carcinogenesis. The finding of alterations in the methylation pattern of genes studied and its association with prognostic factors is a helpful tool in the search for new criteria in clinical and therapeutic decision making.

Adult↗

[Detection of human papilloma virus in cytologic samples or biopsies of the cervix].

BACKGROUND: The DNA quality for the detection and typification of Human Papilloma Virus (HPV) varies according to the type of sample in which it is studied. This may affect the sensitivity and specificity of the method employed. AIM: To study the yield and specificity of HPV detection and typification in uterine cervical samples obtained by cervical brushing fresh frozen and formalin fixed tissue. MATERIAL AND METHODS: Cytological, fresh frozen and fixed tissue samples from 44 patients (nine with low grade lesions and 35 with high grade lesions) were studied. Nested polymerase chain reaction for genes E6/E7 was used to typify HPV groups as low risk or high risk. RESULTS: Of all the cytological samples obtained by brushing 84% of fixed samples and 43% of fresh frozen samples were positive for HPV. The yields were significantly different when comparing brushing with fixed tissue or fresh frozen tissue and fixed tissue with fresh frozen tissue (p <0.05). The frequency of high risk HPV fluctuated from 41% in fresh frozen tissue to 98% in cytological samples. Low risk HPV was detected in 16% of fresh frozen tissue and 68% of cytological samples. A mixed infection was detected in 66%, 41% and 14% of cytological, fresh frozen and fixed tissue samples respectively. CONCLUSIONS: Cytological samples obtained by brushing had the highest yield for the detection of cervical infection with HPV.

Biopsy↗

Microsatellite instability in preneoplastic and neoplastic lesions of the gallbladder.

BACKGROUND: Gallbladder cancer is very common in Chile and is the leading cause of cancer deaths in women aged over 40 years. However, there is limited information about the molecular changes involved in its pathogenesis. Microsatellite analysis was performed using polymerase chain reaction (PCR)-based assays to identify genetic loci that were altered in neoplastic and preneoplastic conditions of early and advanced gallbladder cancer. Our findings were then correlated with clinicopathological variables and survival time. METHODS: We selected 59 surgical specimens of gallbladder adenocarcinomas (29 early cancers and 30 advanced cancers) and 22 surgical specimens from patients with chronic cholecystitis from a high-risk area for gallbladder cancer (Temuco, Chile). Laser capture microdissection (LCM) was used to harvest tumor cells and preneoplastic lesions. Microsatellite analysis was performed using 13 different markers. The tumors and preneoplastic lesions were also examined with immunohistochemistry for hMLH1, hMSH2, and hMSH6. RESULTS: We found that 10% (6/59) of gallbladder cancers showed high-frequency microsatellite instability (MSI-H), with identical proportions in both early and advanced cancers. In premalignant lesions adjacent to the six MSI-H tumors, we detected instability in two of six examples of intestinal metaplasia (33%) and five of six examples of dysplasia (83%). All MSI-H cases showed an altered pattern with the antibodies studied. MSI status was not associated with survival or other clinicopathological features. No MSI or immunohistochemical alterations were found in the chronic cholecystitis group. CONCLUSIONS: Microsatellite instability was observed in equal proportions in early and late cancers, and it was also found in premalignant lesions, indicating that inactivation of mismatch repair genes occurs early in gallbladder carcinogenesis.

Adenocarcinoma↗

[Neoadjuvant chemoradiotherapy in gallbladder cancer].

BACKGROUND: Gallbladder cancer is generally associated with a poor prognosis, being local recurrence the main pattern of failure. AIM: To evaluate neoadjuvant chemoradiation as a means to improve the prognosis in gallbladder cancer. PATIENTS AND METHODS: Twenty three gallbladder cancer patients were prospectively treated between June 1993 and September 1999 in the Temuco Regional Hospital. Eighteen (82%) patients had subserosal infiltration, while three (13%) had serosal and two (9%) adipose tissue infiltration. Chemotherapy was done with 5-fluorouracil in continuous infusion during 5 days at day 1 and 28 of treatment. Radiotherapy consisted in a total dose of 4500 cGy, divided in 25 sessions. Patients' survival was compared with a series of 19 patients not subjected to chemoradiation, formerly treated at the institution. RESULTS: Twenty patients had hematological problems secondary to the therapy. Leucopenia and thrombocytopenia were the most common toxic effects and eight had leucopenia under 2.0 x 10(3) during the treatment course. Chemoradiation delayed surgical treatment in eight patients. After the chemoradiation protocol, seven patients were excluded from surgical treatment and 14 patients underwent resection. Three of the latter (11%) had liver involvement and four (14%) had lymph node involvement. Among the patients who underwent resection, five are still alive with a follow up of 43.8 months. Treated patients had a worst actuarial survival than subjects not treated with chemoradiation. CONCLUSIONS: In this series of patients chemoradiation had no positive effect and a potentially detrimental effect in patients with gallbladder cancer.

Adult↗

[Management of gallbladder cancer with invasion of the muscular layer].

BACKGROUND: Gallbladder cancer is the leading cause of death of cancer among women in Chile. Detection of early forms of the disease during the pathological study of the cholecystectomy specimen is common. The management of these cases, specially those with invasion of the muscular layer is under discussion. AIM: To analyze the clinical features of patients with gallbladder cancer and muscular layer invasion and their prognosis after a simple cholecystectomy. PATIENTS AND METHODS: We studied a series of 46 patients with gallbladder cancer and invasion of the muscular layer. In the majority of cases diagnosis was performed at the moment of specimen study. Eleven patients underwent reoperation. Of these, ten underwent lymphadenectomy and liver resection while one patient underwent resection of the cystic duct stump. RESULTS: During follow up, five patients died as a consequence of gallbladder cancer. Overall survival was 78%, with no differences between patients subjected or not a new operation. CONCLUSIONS: Gallbladder cancer with muscular infiltration has a good prognosis, independent of the type of therapy.

Adult↗

[Association between Helicobacter pylori genotype and the severity of gastritis in infected adults].

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

Adult↗

[K-ras gene mutation in gallbladder carcinoma].

BACKGROUND: Different K-ras mutation frequencies in gallbladder cancer have been reported. AIM: To study the frequency of K-ras gene mutations in advanced gallbladder carcinoma not associated to anomalous junction of pancreatic-biliary duct (AJPBD). MATERIAL AND METHODS: 33 formalin fixed paraffin embedded samples of gallbladder carcinoma (30 women, age range 32-86 years) were selected. Pancreatic cancer tissue with K-ras mutations was used as control. DNA was extracted from the histological section by mean of microdissection and K-ras mutations in codon 12 were detected by polymerase chain reaction and restriction fragment length polymorphism (RFLP), using previously reported technique. RESULTS: Most cases were poorly differentiated adenocarcinomas. K-ras mutation was detected in 10 cases (30%) samples. No differences in K-ras mutation frequency between subserous and serous tumors were detected and no relation between histological features and the mutation was observed. CONCLUSIONS: K-ras mutation in codon 12 is present in 30% in our advanced gallbladder carcinomas. The study of K-ras mutation in preneoplastic lesions and early carcinonmas will be important to determine the role of this gene in the gallbladder carcinogenesis in Chile.

Adenocarcinoma↗

[Promoter methylation profile in breast cancer].

BACKGROUND: Genomic DNA methylation, mutations and allelic deletions explain the inactivation of genes involved in cell proliferation and cell cycle control mechanisms. AIM: To analyze the methylation pattern of important genes related to different carcinogenic mechanisms in patients with breast cancer and the relationship with its biological behavior. MATERIAL AND METHODS: Seventy fresh-frozen breast cancer samples were selected. The methylation specific PCR (MSP) test was used to analyze promoter methylation status for genes CDKN2A (p16), hMLH1, APC, CDH1 (Cadherin E) and FHIT. RESULTS: We found methylation in at least one of the genes studied in 88% of cases and in 3 or more genes in 40.5% of cases. The frequencies of promoter hypermethylation of CDKN2A, hMLH1, APC, CDH1 and FHT were 41.4%, 11.4%, 52.9%, 70% and 42.9%, respectively. We found a relationship between CDKN2A methylatlon 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 larger tumor size (p<0.05), FHIT methylatton and lack of estrogen rectptor IHC expression (p<0.05). CONCLUSIONS: The high frequency of promoter methylation in patients with breast cancer confirms its role in breast carcinogenesis. The finding of alterations in the methylation pattern of genes studied and its association with prognostic factors is a helpful tool in the search of new criteria for clinical and therapeutic decision making.

Acid Anhydride Hydrolases↗

[Inactivation of CDKN2A gene (p16) in gallbladder carcinoma].

BACKGROUND: The CDKN2A gene encodes a cyclin dependent kinase inhibitor, p16, which promotes cell cycle arrest. Methylation of the promoter region transcriptionally inactivates the gene. AIM: To study the relationship between methylation status of the prometer region of p16 gene, the immunohistochemical expression of p16 and clinical and morphological features of gallbladder carcinoma. MATERIAL AND METHODS: We analyzed the methylation status of the promoter region of the CDKN2A gene in gallbladder adenocarcinomas using methylation specific PCR (MSP). We also used microsatellite markers near the CDKN2A gene to detect allelic imbalance (AI) and examined the tumors by immunohistochemistry (IHC) for p16 expression. RESULTS: Of 38 gallbladder adenocarcinomas analyzed by IHC, 11 cases (29%) were negative for p16 protein. Nine (24%) had methylation of the promoter region of the CDKN2A gene. Twenty nine cases were negative for methylation, but four (14%) of these 29 exhibited AI at one or more of the microsatellite markers. CDKN2A promoter methylation was not associated with microsatellite instability (MSI-H). CONCLUSIONS: The inactivation of CDKN2A by methylation and/or deletion might play an important role in gallbladder carcinogenesis.

Adult↗

[Point mutation of TP53 suppressor gene in pre-neoplastic and neoplastic lesions of the stomach].

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

Adenocarcinoma↗

[Primary hyperthyroidism after excision of a Struma ovarii].

Struma ovarii is a teratoma composed of thyroid tissue and can be a rare cause of hyperthyroidism. We report a 35 years old woman with a left ovarian mass whose pathology revealed a Struma ovarii. This tumor was partially excised initially to avoid fertility problems and after a successful gestation, the tumor was completely removed during a cesarean section. Sixty days after delivery a hypothyroidism was diagnosed. Levothyroxine was started and euthyroidism was achieved.

Adult↗