The study by researchers at the University of Toronto found childhood physical abuse is associated with a 49 per cent higher chance of developing cancer in adulthood.
Principal researcher Esme Fuller-Thomson says there are many possible but unproven reasons physical abuse might increase the risk of cancer.
One theory suggests that ongoing stress raises levels of the "fight or flight" hormone cortisol, which may suppress the immune system's ability to detect and destroy cancer cells.
The study found the link between childhood abuse and cancer remained high even after adjusting for adult health behaviours such as smoking and alcohol consumption.
Fuller-Thomson stresses that most abused children do not develop cancer, but she says more research is needed to explain the higher cancer rates the study found.
The study used data from the Canadian Community Health Survey and will be published in next month's issue of the journal Cancer.