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Master's Dissertation
DOI
https://doi.org/10.11606/D.99.2016.tde-02062016-103832
Document
Author
Full name
Cristiane de Campos Centrone
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2016
Supervisor
Committee
Levi, José Eduardo (President)
Longatto Filho, Adhemar
Nicolau, Sérgio Mancini
Title in Portuguese
Detecção de DNA de HPV no plasma para potencial identificação precoce de recidiva de câncer do colo de útero
Keywords in Portuguese
HPV
Marcador molecular
Neoplasias do colo uterino
Plasma
Reação em cadeia por polimerase
Recidiva
Abstract in Portuguese
O câncer do colo do útero constitui a terceira neoplasia maligna mais comum na população feminina, com aproximadamente 520 mil novos casos e 260 mil óbitos por ano e origina-se a partir da infecção genital persistente pelo Papiloma Vírus Humano (HPV) oncogênico. Os principais HPVs considerados de alto risco oncogênico são os tipos HPV-16 e 18, responsáveis por cerca de 70% de todos os casos de cânceres cervicais (CC) no mundo. Pacientes com CC apresentam taxa de recidiva variando de 8% a 49%. Dentro de dois anos de seguimento, 62% a 89% das recidivas são detectadas. Atualmente, os testes usados para detecção de recidiva são a citopatologia da cúpula vaginal e exames de imagem, porém ainda não estão disponíveis testes específicos. O DNA livre-circulante (cf-DNA) representa um biomarcador não-invasivo facilmente obtido no plasma e soro. Vários estudos mostram ser possível detectar e quantificar ácidos nucléicos no plasma de pacientes com câncer e que as alterações no cfDNA potencialmente refletem mudanças que ocorrem durante a tumorigênese. Essa ferramenta diagnóstica não-invasiva pode ser útil no rastreio, prognóstico e monitoramento da resposta ao tratamento do câncer. Portanto, o desenvolvimento e a padronização de testes laboratoriais não invasivos capazes de identificar marcadores tumorais e diagnosticar precocemente a recidiva da doença aumentam a chance de cura através da utilização dos tratamentos preconizados. Sendo assim, este estudo tem o objetivo de detectar o DNA de HPV no plasma de pacientes com CC para avaliar sua potencial utilidade como marcador precoce de recidiva. Um fragmento de tumor e sangue de pacientes com CC, atendidas no ICESP e HC de Barretos, foram coletados antes do tratamento. Entraram no estudo 137 pacientes nas quais o tumor foi positivo para HPV-16 ou 18, sendo 120 amostras positivas para HPV-16 (87,6%), 12 positivas para HPV-18 (8,8%) e cinco positivas para HPV-16 e 18 (3,6%). A média de idade das pacientes deste estudo foi de 52,5 anos. Plasma de 131 pacientes com CC da data do diagnóstico e de 110 pacientes do seguimento foram submetidas ao PCR em Tempo Real HPV tipo específico. A presença do DNA de HPV no plasma pré-tratamento foi observada em 58,8% (77/131) com carga viral variando de 204 cópias/mL a 2.500.000 cópias/mL. A positividade de DNA no plasma pré-tratamento aumentou com o estadio clínico do tumor: I - 45,2%, II - 52,5%, III - 80,0% e IV - 76,9%, (p=0,0189). A presença do DNA de HPV no plasma pós-tratamento foi observada em 27,3% (30/110). A média de tempo das recidivas foi de 3,1 anos (2,7 - 3,5 anos). O DNA de HPV foi positivo até 460 dias antes do diagnóstico clínico da recidiva. As pacientes com DNA de HPV no plasma apresentaram pior prognóstico, tanto sobrevida como o tempo livre de doença, em relação às que foram negativas. Nas pacientes com CC a presença de HPV no plasma de seguimento pode ser um marcador precoce útil para o monitoramento da resposta terapêutica e detecção de pacientes com risco aumentado de recidiva e progressão da doença.
Title in English
Detection of HPV DNA in plasma samples as a potencial early marker of cervical cancer recurrence
Keywords in English
Cervical neoplasms
HPV
Molecular marker
Plasma
Polymerase chain reaction
Recurrence
Abstract in English
Cervical cancer (CC) is the third most common malignancy in the female population, with approximately 520,000 new cases and 260,000 deaths per year. It is caused by a persistent genital infection with oncogenic Human Papillomavirus (HPV). The HPV-16 and 18 types are considered of high risk and account for about 70% of all cases in the world. Patients with CC have a relapse rate ranging from 8% to 49%. Within two years of follow up, 62% to 89% of relapses are detected. Nowadays, the tests used to detect recurrence are cytopathology from the vaginal vault and imaging tests, but there are no available specific tests yet. The cell-free circulating DNA (cf-DNA) is a non-invasive biomarker easily obtained from plasma and serum. Several studies have shown the possibility to detect and quantify nucleic acids in the plasma of cancer patients and that the changes in cf-DNA potentially reflect the changes that occur during tumorigenesis. This non-invasive diagnostic tool may be useful in screening, prognosis and monitoring response to treatment. Therefore, the development and standardization of non-invasive laboratory tests that are able to identify tumour markers and to make early diagnosis of the disease recurrence increase the chance of cure by appropriate treatments. Accordingly, this study aims to detect HPV DNA in the plasma of patients with CC to assess its potential utility as an early marker of recurrence. A tumour biopsy and blood of patients with CC, attended in ICESP and HC Barretos, were collected before treatment. 137 patients entered the study tumour being positive for HPV-16 or 18, 120 samples positive for HPV-16 (87.6%), 12 positive for HPV-18 (8.8%) and five positive for HPV -16 and 18 (3.6%). The average age of patients in this study was 52.5 years old. Plasma from patients with CC, 131 from the date of diagnosis and 110 from follow-up of were subjected to Real-Time PCR HPV type-specific. The presence of HPV DNA in plasma pre-treatment was observed in 58.8% (77/131) with viral load ranging from 204 copies / ml to 2,500,000 copies / mL. The DNA positivity in the pre-treatment plasma increased with advancing clinical tumour stage: I - 45.2%, II - 52.5%, III - 80.0% IV - 76.9%, (p = 0.0189). The presence of HPV DNA in the post-treatment plasma was observed in 27.3% (30/110). The average time of relapse was 3.1 years (2.7 to 3.5 years). HPV DNA was positive for up to 460 days before clinical diagnosis of recurrence. Considering survival and remission analysis, the patients who had the presence of HPV DNA in plasma had a worse prognosis compared to those who were negative. The overall survival and remission interval showed a significant association between the presence of HPV DNA in plasma and recurrence of the disease, indicating that in patients with CC HPV DNA in the plasma can be a useful early marker for monitoring and detection of the therapeutic response of patients at increased risk of relapse and progression of the disease.
 
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CrisCentrone2016.pdf (2.15 Mbytes)
Publishing Date
2016-06-03
 
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