Grant: Op Gr: Data Analysis Using Existing Databases n Cohorts-Cancer Prevention n Ctrl

Cancer, autoimmune disease, and allergies all involve problems with a person's immune system. Researchers have long noted that allergies, asthma, and certain autoimmune diseases frequently appear together in the same person or among family members. Yet it is unclear if childhood cancer also appears more or less frequently in families where children have problems with their immune system, such as autoimmune disease or severe allergies. Very little is known about what causes cancer in children and a better understanding how these diseases cluster together in siblings will be helpful in understanding how the immune system is involved in childhood cancer. In this study, we will examine if siblings of children with immune-related diseases, such as celiac disease, type 1 diabetes, severe allergies and asthma, have a higher or lower risk of cancer. We will use a large dataset containing all children born in hospitals in Quebec, Canada. We will identify brothers and sisters, and will see which children were diagnosed with an autoimmune disease or severe allergy. We will compare these children with those whose siblings did not have an autoimmune disease or severe allergy. We will determine if children from families with autoimmune disease or severe allergy have a higher or lower chance of having a sibling with cancer. As this project will help understand how cancer, autoimmune disease and allergies are inter-linked in families, our results will bring us one step closer to understanding the potential genetic and environmental risk factors for these diseases, particularly why some children get cancer and what can be done to prevent it.