ABSTRACT
Several studies have been published concerning Epstein-barr virus (EBV) infection and nasopharyngeal cancer (NPC) development. The incidences of histological types are different according to endemic or non-endemic regions. Latent EBV infection is found in almost all cases of NPC in endemic regions, but normally absent in type I carcinomas, more common in non-endemic regions. AIM: The purpose of this hospital-based study was to analyze the presence of EBV in nasopharyngeal tumor tissues and in peripheral blood of nasopharyngeal cancer patients and healthy individuals, in a low risk, non-endemic area. METHODS: EBV detection in samples of nasopharyngeal cancer patients and healthy individuals. RESULTS: This study indicates that the frequency of EBV positive cases in peripheral blood is higher in advanced tumor stages. CONCLUSIONS: The incidence rates of NPC have a distinct distribution. Since the prevalence of this disease is low in occidental countries, little is known about the biology of these tumors in non-endemic areas. We observed statistically significant differences in EBV detection between the NPC patient group and the control group. This study may help to understand the biological mechanisms of NPC and the correlation of EBV infection with this disease, in a low risk, non-endemic region.
Têm sido publicados vários estudos acerca da infecção por Epstein-Barr vírus (EBV) e o desenvolvimento de carcinoma da nasofaringe (NPC). As prevalências dos tipos histológicos e a presença de infecção latente pelo EBV são diferentes em regiões endémicas e não endémicas. OBJETIVO: O objectivo deste estudo consistiu na detecção de EBV em tecido tumoral da nasofaringe e sangue periférico de doentes com NPC e em indivíduos saudáveis, provenientes duma área não-endémica, de baixo risco. MÉTODOS: Detecção de EBV em amostras de doentes com carcinoma da nasofaringe e indivíduos saudáveis. Neste estudo de série foram avaliadas as implicações clínicas da presença de EBV circulante no sangue periférico de doentes com carcinoma da nasofaringe. RESULTADOS: Este estudo indica que a frequência de casos EBV positivos detectados no sangue periférico é superior em tumores de estádio mais avançado. CONCLUSÕES: Estes resultados indicam que se observam diferenças na pesquisa do vírus Epstein-Barr no grupo de doentes com NPC e no grupo controlo, sem tumor. Este estudo pode ajudar na compreensão dos mecanismos biológicos do cancro da nasofaringe e da correlação destes tumores com a infecção por EBV numa área não-endémica, de baixo risco.
Subject(s)
Adolescent , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Young Adult , DNA, Viral/analysis , Epstein-Barr Virus Infections/diagnosis , /isolation & purification , Case-Control Studies , Nasopharyngeal Neoplasms/virology , Polymerase Chain Reaction , Young AdultABSTRACT
Breast cancer is the leading cause of death among women in developing countries. In Portugal, it presents the highestincidence and mortality rates in women diseases. About 10% of breast cancer is inherited, presenting a family pattern ofincidence, and have been attributable to mutations in high penetrance susceptibility genes, such as BRCA1 and BRCA2.However, BRCA1 and BRCA2 mutations account only for around 25% of families with inherited breast cancer. Many environmentalfactors have been associated with risk of breast cancer development, such as ionized radiation, chemical carcinogens (diet andenvironment). These mutagens sources, together with endogenous and exogenous estrogens, produce a range of DNA lesionssuch as reactive oxygen species, oxidized bases, bulky DNA adducts and DNA strand breaks. Therefore, DNA repair capacitydetermines cellular susceptibility to endogenous and exogenous substances and factors. The response of cells to DNA damageand their ability to maintain genomic instability by DNA repair are crucial in preventing cancer initiation and progression. Somestudies have demonstrated a strong association of higher levels of DNA damage and lower DNA repair capacity in breast cancerpatients and healthy women with a positive family history of breast cancer. Several polymorphisms have been described in DNAsignalling and repair genes. Therefore, although each polymorphism may be associated with a small increased risk for breastcancer in an individual, the risk attributable in the population as a whole is likely to be higher than for rare, high-penetrancesusceptibility genes. In this review, we intend to illustrate the state of the art in studies concerning DNA signalling or repairgenetic polymorphisms and breast cancer susceptibility.