The study, which was based on over seven billion DNA sequences found no genetic traces of viruses in these forms of cancer.
It has been scientifically proven that about 15 per cent of all cancer cases are the result of viral infection, but many researchers believe that even more cancers could be caused by viruses.
Among other theories, it is suggested that the Epstein-Barr virus could be a possible cause of breast cancer and that the cytomegalovirus might cause the malignant brain tumour glioblastoma.
Erik Larsson, who is a researcher at the Sahlgrenska Academy at the University of Gothenburg, said that there is some controversy in that they have not found any viruses in these forms of cancer, but if there were any viral involvement in breast cancer and glioblastoma, it is likely that they would have found some trace of it.
The study was published in the highly-regarded scientific journal "Nature Communications". The study involved the researchers using powerful computers to conduct in-depth analysis of 700 billion DNA sequences from more than 4,000 tumours.
The study has been published in Nature Communications.
--ANI (Posted on 10-10-2013)