Detecção e genotipagem de HPV em carcinomas de células escamosas de cabeça e pescoço (CCECP)

Abstract

Resumo: Os carcinomas de celulas escamosas de cabeca e pescoco (CCECP) sao o sexto tipo de tumor mais comum mundialmente. Embora o consumo de tabaco e alcool estejam associados com a maioria desses tumores, o aumento na incidencia de casos em regioes anatomicas especificas sugere que a infeccao por certos tipos de papilomavirus humano (HPV) de alto risco, possa ser responsavel por um distinto grupo de neoplasias de cabeca e pescoco. Este estudo refere-se a investigacao da prevalencia e do perfil da infeccao por HPV em casos de CCECP, de pacientes atendidos em um hospital terciario na regiao Sul do Brasil. Trata-se de um estudo de coorte retrospectiva, analitico, observacional. Foram avaliadas 130 amostras de material incluido em parafina, que foram submetidas ao isolamento do DNA e a deteccao do material genetico do HPV por meio de PCR touchdown. A genotipagem do HPV foi realizada por meio de sequenciamento nucleotidico. Os resultados mostraram que a mediana de idade da populacao estudada foi de 60 anos (15,75), com 76,2% (n=99) de casos diagnosticados a partir da quinta decada de vida. A maior parte dos casos foi de homens (86,9%, n=113) e 79,2% (n=103) dos casos estudados apresentaram cor da pele branca. O HPV foi identificado em 24,6% (n=32) das amostras analisadas, sendo os tipos mais prevalentes o HPV-6 (75%, n=24), 11 (44%, n=14), 53 (9,4% n=3), 35 (9,4% n=3). A baixa escolaridade apresentou-se como um fator de protecao a infeccao por HPV (p=0,007; OR: 0,036 a 0,523). Os tumores de labio e cavidade bucal representaram 59,4% (n=19) dos casos HPV positivos, os de orofaringe 9,4% (n=3) e os de laringe 25% (n=8), sendo que na cavidade bucal, 52,6% (n=10) dos casos HPV positivos eram de tumores de lingua e assoalho bucal. Dos casos HPV positivos, 87,5% (n=28) receberam tratamento combinado e 62,5% (n=20) foram a obito. Foram identificados 30 tipos de HPV dos generos alpha, beta e gamma, sendo a maioria das infeccoes por HPV do genero alpha (93,8%, n=30). Labio e cavidade bucal foram os unicos sitios com infeccoes por HPV do genero gamma. Nao foram encontradas infeccoes por HPV do genero beta nos casos de obito. Para as mono-infeccoes (25%, n=8), o sitio mais prevalente foi a laringe (9,4%, n=3), e para as infeccoes multiplas (75%, n=24), labio e cavidade bucal (53,1%, n=17). Nao ter cor da pele branca mostrou-se ser um fator de protecao contra infeccoes multiplas (p=0,006; OR: 0,023 a 0,48; IC 95%). A frequencia de infeccao pelo HPV encontrada neste estudo mostrou-se acima do encontrado em estudos com outras populacoes brasileiras, mas de acordo com a media encontrada em relatos de meta-analise. A baixa escolaridade apresentou-se como um fator de protecao a infeccao por HPV, e nao ter cor da pele branca mostrou-se ser um fator de protecao contra infeccoes multiplas por HPV. Mais estudos sao necessarios para conhecer a historia natural da infeccao por HPV e sua associacao com o desenvolvimento de neoplasias de cabeca e pescoco. Palavras-chave: Papilomavirus humano. Cancer de cabeca e pescoco. Genotipos. Reacao em cadeia da polimerase.

Abstract: Head and neck squamous cell carcinomas (HNSCC) are among the world's most common cancers. Although tobacco and alcohol consumption are associated with the majority of these tumors, increasing trends in the incidence at specific sites suggest that infection by certain high-risk types of human papilloma viruses (HPV) is responsible for a distinct set of head and neck tumors. This work investigated the prevalence and clinic profile of HPV infection in HNSCC at a tertiary hospital in Southern Brazil. It is a cohort retrospective observational and analytical study. DNA isolation of 130 formalin-fixed paraffin-embedded (FFPE) samples was performed, and HPV detection was assessed through touchdown PCR. HPV DNA genotyping was performed through sequencing. The results showed that the median age of patients was 60y (15.75), with 76.2% (99/130) of the cases diagnosed after the fifth decade of life. Most of the cases were in males (86.9%, 113/130) and 79.2% (103/130) of the cases were among whites. HPV DNA was identified in 24.6% (32/130) of the samples, with the most prevalent HPV types being HPV-6 (75%, 24/32), 11 (44%, 14/32), 53 (9.4%, 3/32) and 35 (9.4%, 3/32). Having a low educational level was a protective factor against HPV infection (p=0.007; OR: 0.036-0.523). Lip and buccal cavity tumors represented 59.4% (19/32) of the HPV positive cases, oropharynx tumors were 9.4% (3/32) and larynx tumors were 25% (8/32). Among lip and buccal cavity tumors, 31.6% (6/19) were in the tongue region. Among the HPV positive cases, 87.5% (28/32) received combined treatment and 62.5% (20/32) died. Thirty HPV types from alpha, beta and gamma genera were identified and most of the infections were with HPV from the alpha genus (93.8%, 30/32). Lip and buccal cavity were the only sites with HPV of the gamma genus. Also, the gamma genus was only detected in tumors staged as T3 and T4, and in well or moderately differentiated cases. No HPV infection from the beta genus was detected among those patients who died. Among single HPV infections (25%, 8/32), larynx was the most prevalent site (9.4%, 3/8), and among multiple HPV infections (75%, 24/32), lip and buccal cavity (53.1%, 17/32) were the most prevalent ones. Not being white was a protective factor against multiple HPV infections (p=0.006, OR: 0.023-0.48, IC 95%). The frequency of HPV infection found in this work was higher than the ones found among other brazilian populations but is in accordance with the media value found in meta-analysis studies. Low educational levels were a protective factor against HPV infection and not being white was a protective factor against multiple HPV infections. Additional prospective studies are needed to know the natural history of mixed HPV infection and its association with the development of head and neck neoplasia. Keywords: Human papillomavirus. Head and neck cancer. Genotypes. Polymerase chain reaction.