It is true that we still do not know for sure why our children get cancer. Scientists are also asking the same questions. It is generally believed that the childhood cancer is caused by a complex interaction of genetic and environmental factors that the scientists do not fully understand yet. As numerous studies have been made to detangle the complex nature of cancer, it is becoming more evident that certain environmental and genetic factors may only affect cancer when combined. Environmental factors are normally examined in population-based studies. Due to the limited evidence or inconclusive results, researchers are giving great focus on the gene-environment interaction studies - this is where they investigate some genetic variants that may cause cancer when they are combined with specific environmental exposures, which otherwise may not be risk factors for childhood cancer.
Although it is difficult to unravel the environmental factors causing childhood cancer in population studies it does not mean that we have to stop such studies. Population studies give us clues on where to focus our detailed clinical research.
There are several well-established environmental causes of childhood cancer. The earliest known exposures were radiation, diethylstilbestrol and some chemotherapeutic agents. The studies of Japanese children who were exposed to atomic bomb radiation have found that these children, as they grew, had higher rates of childhood leukaemia than unexposed children. Many other agents such as electromagnetic fields, pesticides and some parental occupational exposures are suspected of playing roles, but the evidence is not yet conclusive.
Below is the list of potential causes that researches have studied to date. We have divided these studies into three time periods.
