More work is needed to develop a vaccine against Epstein-Barr Virus (EBV), which is linked to a number of cancers, it said.
Research funded by the charity led to the identification of the virus and its association with cancer 50 years ago.
Cancer Research UK scientist Professor Alan Rickinson, from the University of Birmingham, said: "We now know so much about how the virus contributes to the development of particular types of cancer.
"The next big challenge is to develop a vaccine that will prevent infection by the virus."
Around 95% of the global adult population is infected with EBV. Many people pick up the virus in childhood and carry it for life with no ill effects.
Others infected as teenagers may develop glandular fever but make a full recovery - but in some individuals the virus can trigger cancer.