Indeed, cases of cancer that are not tied to smoking or aging are increasing. Cancer is the leading cause of death in middle-aged persons and children (after accidents), and we can’t explain why, for most forms of cancer, death rates are higher for blacks than they are for whites.
的确，与吸烟和衰老无关的癌症病患正在增加。癌症是造成中年人和儿童（仅次于事故）死亡的主要原因。而且我们不能解释为什么对于大多数种类的癌症黑人的死亡率要高于白人。