The development of specific monoclonal antibodies anti-ROR1 allowed a careful analysis of ROR1 positivity in various ovarian epithelial cancers, showing that 90% of endometrioid adenocarcinomas are ROR1+, 77% of HGS-OvCa papillary carcinomas are ROR1+, 44% of mucinous adenocarcinomas are ROR1+, while clear cell carcinomas are ROR1− [225]. This evidence concerns the gene ROR1 and endometrioid adenocarcinoma.