If proved, the information could lead to a preventative vaccine and therapies to cure many forms of the disease.
Scientists had discovered hepatitis B and C viruses can cause liver cancer and human papilloma virus (HPV) which can cause cervical cancer.
But the new research study using DNA analysis has shown that viruses could be implicated as the cause in 40 per cent of the 200 forms of cancer.
German virologist Harold Zur Hausen, who jointly discovered the link between cervical cancer and HPV, said in the paper the discovery could be ground-breaking.
He said: 'Although we know that currently slightly more than 20 per cent of the global cancer incidence is linked to infectious events, some epidemiological observations suggest that this this percentage may increase'.
The discovery could be life-changing with the possibilities of vaccinations against the key viruses, cutting the number of cancer sufferers - however the cost of development and trials will be enormous.