Scientists have found further compelling evidence infections such as colds may trigger childhood cancers.
Some 3,000 cases of child cancer were analysed
The University of Newcastle-led team looked at 3,000 childhood cancers in 0 to 14-year-olds from 1954 to 1998, the European Journal of Cancer reported.
Researchers found unusual clusters of brain tumours and leukaemia which were typical of infection-related disease.
But children would need genetic factors to make them susceptible, they added. Experts said more evidence was needed.
The team found a pattern emerged where by the types of cancer repeatedly occurred at similar times and geographical locations, known as "space-time clustering".
Disease caused by more constant environmental factors produce clusters of cases in one place over a much longer period of time.
Even when chance was taken into account, cancer rates were 8% higher than would be expected.
It was even possible infections caught by mothers while pregnant could trigger the cancers, the report said.
But the researchers stressed the findings did not mean people could "catch cancer".
People affected by infections would need to carry mutant cells which could be manipulated by viruses, causing a second mutation and prompting the onset of cancer.
Lead researcher Dr Richard McNally said: "We found that place of birth was particularly significant, which suggests that an infection in the mother while she is carrying her baby, or in a child's early years, could be a trigger factor for the cancer.
"These could be minor, common illnesses that are not even reported to the GP, such as a cold, mild flu or a respiratory virus."
But he added while the research was important, it was just another "piece in the jigsaw".
The team looked at recorded cases of cancer from Manchester Children's Tumour Register spanning five decades.
The register covers areas of southern Cumbria, Lancashire, Greater Manchester, North West Derbyshire and North Cheshire.
The research is the latest of a number of studies that have made a link between infections and cancer.
In April, a Leukaemia Research Fund study found that children introduced to nursery before the age of one were found to be at lower risk of leukaemia.
Dr David Grant, scientific director at Leukaemia Research Fund, said the findings confirmed the fund's earlier study.
He added: "The timing of exposure to common infections in infancy and later in childhood is critically important."
But Professor John Toy, medical director of Cancer Research UK, which helped fund the study, said: "These findings provide more clues to a link between viruses and some types of childhood cancer, but we need more evidence before we can be sure."