The Frequency and Type of K-RAS Mutations in Mexican Patients With Colorectal Cancer: A National Study.

BACKGROUND: Current metastatic colorectal cancer (mCRC) therapy uses monoclonal antibodies against the epidermal growth factor receptor. This treatment is only useful in the absence of K-RAS gene mutations; therefore the study of such mutations is part of a personalized treatment. The aim of this work is to determine the frequency and type of the most common K-RAS mutations in Mexican patients with metastatic disease by nucleotide sequencing. PATIENTS AND METHODS: We studied 888 patients with mCRC from different regions of Mexico. The presence of mutations in exon 2, codons 12 and 13, of the K-RAS gene was determined by nucleotide sequencing. RESULTS: Patients exhibited K-RAS gene mutations in 35% (310/888) of cases. Mutation frequency of codons 12 and 13 was 71% (221/310) and 29% (89/310), respectively. The most common mutation (45.7%) in codon 12 was c.35G>A (p.G12D), whereas the one in codon 13 was c.38G>A (p.G13D) (78.7%). DISCUSSION: Given the frequency of K-RAS mutations in Mexicans, making a genetic study before deciding to treat mCRC patients with monoclonal antibodies is indispensable.

HLA-DRB1 Class II antigen level alleles are associated with persistent HPV infection in Mexican women; a pilot study.

BACKGROUND: Persistent infection with high-risk human papillomavirus (HPV) is a major risk factor for malignant lesions and cervical cancer. A widely studied element in the search for genetic factors influencing risk HPV infection diseases is allelic variation of the human leukocyte antigen (HLA) locus. The study was designed to search for HLA susceptibility alleles contributing to the persistence of HPV infection in Mexican women. METHODS: A total of 172 subjects were divided into three groups: 1) HPV-persistent patients; 2) HPV-cleared; and 3) HPV-reinfected patients. They were screened for HPV types using a polymerase chain reaction (PCR). PCR-sequence specific oligonucleotide probes (PCR-SSOP) was used for HLA DRB1 and DQB1 typing. RESULTS: We observed that HLA-DQB1*0501 allele might be associated with susceptibility of reinfection with HPV (p = 0.01, OR = 4.9, CI 95% = 1.3 -18.7). Allele frequency of HLA-DRB1*14 was particularly reduced in patients with cancer when compared with the HPV-persistent group (p = 0.04), suggesting that this allele is a possible protective factor for the development of cervical cancer (OR = 2.98). HLA-DRB1*07 might be associated with viral clearance (p = 0.04). CONCLUSIONS: Genetic markers for HPV infection susceptibility are different in each population, in Mexicans several HLA-DQB1 alleles might be associated with an enhanced risk for viral persistence. In contrast, DRB1*14, seems to confer protection against cervical cancer.

Carcinoma odontogénico de células claras / Odontogenic carcinoma of clear cells

El carcinoma odontogénico de células claras es un raro tumor odontogénico que se presenta principalmente en la parte anterior de la mandíbula, mayormente en mujeres entre la quinta y séptima década de vida. Se caracteriza histológicamente por redes de células con citoplasma claro mezcladas con células que contienen citoplasma eosinófilo. Es sumamente agresivo y puede presentar metástasis local o a distancia. Al emplearse el tratamiento por enucleación y curetaje, frecuentemente da lugar a recurrencia, por lo que se aconseja el tratamiento radical de resección mandibular hasta una zona libre de lesión. El carcinoma odontogénico de células claras debe ser considerado en el diagnóstico diferencial de tumores mandibulares que presenten células claras para el establecimiento del plan de tratamiento adecuado. Se debe incluir el seguimiento a largo plazo del paciente. Se presenta el caso de un paciente femenino de 69 años de edad, con una lesión presente en la región presinfisaria derecha, sin afectación de ganglios linfáticos regionales o metástasis aparente. Se efectuó osteotomía segmentaria mandibular y reconstrucción con placa de titanio(AU)

Clear cell odontogenic carcinoma is a rare malignant odontogenic neoplasm, with a predilection for the anterior segment of the jaws, and presenting basically in women between the fifth and seventh decades of life. CCOC is composed histopathologycally by strands or groups of cells showing clear cytoplasm associated with cells showing eosinophilic cytoplasm and some times with tall columnar cells that resambled ameloblasts. CCOC is considered a low-grade malignancy but in some cases its behavior is aggressive giving local and distant metastasis, so the recommended treatment is a radical resection and follows the patient very close. CCOC should be diferenciated microscopically from other local and metastatic lesions that are composed with clear cells also, in order to render a proper diagnosis and treatment. We are presenting a clinical case corresponding to a 69 years old female patient, with a 10 year history of a slow growing anterior mandibular lesion without lymph node or distant metastasis, with a biopsy diagnosis of clear cell odontogenic carcinoma, the patient was treated by partial resection of the anterior mandible and reconstructed with a titanium plate(AU)

Importancia de la citología y clínica en el cáncer de cérvix / Cytological and clinical importance in cervix uteri neoplasm

Se instituye un método para el diagnóstico del cáncer de cérvix, evitando estudios histopatológicos para decidir conducta terapéutica. La citología es diagnóstica junto con la clínica en porcentajes de efectividad comparables a lo ortodoxo; pero evitando de esta manera probable diseminación, morbilidad, mortalidad, costos y tiempo a la paciente