AFP and neoplasm: In regard to tumor factors, several studies have reported that more young than old patients have high AFP levels, that is, the rates of cases in which AFP is equal to or exceeds a value of 400 ng/ml range from 52.6 to 82.0%[3,7,9-11,14], and rates for an AFP of ≥10,000 ng/ml range from 31.6 to 60.0%[3,10,11,14].