Putative oncogenic viruses: some data on Brazilian subjects

The concepts of cancer etiology have changed over the years, mainly based on molecular epidemiology studies and bioinformatics approaches. Until relatively recently, the most accepted theory of cancer etiology has dealt with the accumulation of gene mutations and the consequent cognate proteins dysfunction, but now some authors have argued against the proposed theory. The additional role of noncellular genes in the cause of malignancy, associated to environmental factors and host genetic background, has been proposed and mostly accepted by the scientific community. Some of our data from human populations in Brazil concerning cancer epidemiology, molecular and serological surveys, were conducted looking for the detection of putative oncogenic viruses, as the Human T-cell Lymphotropic virus/HTLV-1/2, Human Papillomavirus/HPV, the Mouse or Human Mammary Tumor Virus/MMTV, the Human Endogenous Retrovirus/HERVs and the Hepatitis C virus/HCV, in healthy and malignized human tissues. Generally, research work around the world suggests that 10 to 20 % of all human cancers are etiologically linked to oncogenic viruses, so if the presence of exogenous or endogenous virus sequences in the human DNA has any significancy in the cancer etiology, it deserves further and continuous research work and discussion, always taking in account the human populations in their interacting surrounding environment.