Cancer is a genetic disorder. But not all cancers are heriditary. Only 5-10% cancers are inherited. E.g: mostly the breast and gynaecological cancers.Inheritance depends on the cancer type and the pattern of disease inhertance . If it is an autosomal inheritence ,everyone of your generation will have 50% chance of inheriting the disease. The prevention measures will depend on the type of cancer/syndrome running through your family.