DETECÇÃO E GENOTIPAGEM DE PAPILOMAVÍRUS HUMANO EM TUMORES DE PÊNIS

Abstract

Cancer arises as a consequence of genetic or epigenetic alterations in genes that have a variety of different influences on the cell cycle, including cell growth, proliferation, differentiation, and apoptosis. Nowadays, cancer is among the most prevalent, costly, and preventable of all health problems. In Brazil, it represents the second cause of death of the adult population. Penile cancer is a rare disease, generally more prevalent in poor populations from developing countries, associated with precarious hygiene habits, especially of uncircumcised men. Penile cancer incidence varies across Brazilian geographical regions and it is more common on the North and Northeast regions. Penile cancer usually develops between the fourth and seventh decade of life and Squamous Cell Carcinoma accounts for up to 97% of all penile cancers. Molecular and epidemiological data has found strong evidence of the presence of HPV genome associated with penile carcinomas. The prevalence of HPV genome has been reported to be as high as 80%, depending on the sensitivity of the detection method and the selection of the tumor type. High-oncogenic-risk viral genotypes 16 and 18 are the most common types detected in association with penile tissue. The general objective of the current study was to detect and genotype HPV genome associated with penile cancer tissue using the polymerase chain reaction (PCR) assay. Furthermore, the potential association between the presence of HPV in the samples and the clinicopathological aspects of all cases was also investigated. The study group comprised of 29 cases diagnosed with penile carcinomas at the Urology Department/Hospital Araújo Jorge in Goiânia from 2001 to 2006. Total DNA was isolated from frozen tumor tissue and HPV DNA amplification was performed using GP5+/6+ primer pairs. Samples identified as positive for HPV DNA were genotyped with type-specific primer pairs. Appropriate positive and negative PCR controls were run with all reactions. As an internal control, a fragment of the GAPDH gene was also amplified. In our study, the mean age at the diagnosis was 61,5 years. With respect to tumor topography, 24% was present on the penile shaft, 28% on the glans, 16% on glans and foreskin as the three most frequent observations. Regarding Jackson s staging, 32% of the cases were J-I, 36% J-II, 24% JIII, and 8% J-IV. Partial penectomy was the most frequent surgical approach during treatment, 32% of all cases had metastasis and phimosis was present in 72% of the patients. HPV genome was amplified in 34,5% (10/29) of samples, and HPV-16 was the most prevalent. HPV role in penile cancer must be investigated and viral infection should be considered an import risk facto for penile cancer development, most likely to be implicated in tumor initiation, and should be investigated in association with the occurrence of phimosis, poor hygiene habits, chronic smoking, and individual promiscuity.