Van Hensbergen and his colleagues found that the expression of CD13 in EOC was associated with the histological subtype: CD13 expression in tumor cells was observed in 80% of the patients with a serous carcinoma and 100% of the patients with a mucinous carcinoma and in only 20% of the clear cell carcinoma patients [49,50]. Here, ANPEP is linked to serous adenocarcinoma.