The cancers appear in children who move into the community from elsewhere (which, to me, suggests environmental... and environmental factors have often been linked to cancers)
(from the article)
He added that the study supported a theory developed by Professor Leo Kinlen of Oxford University that childhood leukaemia was caused by infections introduced into a community by migrant workers.
Responding to the findings, Prof Kinlen said the next challenge was "to identify the infective agent, and at the moment scientists have little idea what it could be".
Cancer triggered by viruses is known (hepatitis is a factor in liver cancer and STDs (sexually transmitted diseases) in cervical cancer: www2.cdc.gov...
But the "evidence" here is so vague and I don't see signs that the research controlled for or investigated environmental factors.