The sensitivity and specificity of a new formula to distinguish endometrioid type endometrial carcinoma from ovarian endometrial carcinoma.

Endometrioid type adenocarcinoma sometimes occupies both endometrium and ovary and in some cases the origin cannot be determined.In this study, we established a formula to distinguish ovarian endometrioid cancer (EOC) from endometrioid type endometrial cancer (EEC), based on our previous report of cyclin and KI67 expression pattern by immunohistochemistry of 36 EECc and 37 OECc by the logistic regression. We calculated the diagnostic accuracy using 92 test samples retrospectively and finally could diagnose the origin of 16 cases in whom endometrioid type adenocarcinoma arose in both ovary and endometrium and could be determined by Scully's criteria, and 15 cases in whom endometrioid type adenocarcinoma arose in both ovary and endometrium and Scully's criteria were not useful retrospectively.The estimated formula is as follows: Logit(Prob(EOC))=-1.1437-0.0853 CNA+0.0423 CNB+0.173 CND1+0.0129 CNE+0.0224 CNF+0.0508 KI67, where Prob(EOC) is the probability that a clinical sample is EOC. If Prob(EOC) is larger than 0.5, the diagnosis is ovarian cancer; if less than 0.5 it is endometrial cancer. Finally, using the formula, 37 of 48 EECs (77.1%) and 33 of 44 EOCs (75.0%) were correctly classified, with an accuracy of 76.1% (p<0.0001), retrospectively. In 12 of the 16 cases (75%) who could be determined by Scully's criteria, the origin determined by Scully's criteria was concordant with the origin determined by the formula retrospectively. In the other 15 cases, 12 cases were judged as ovary/ovary, 2 cases were judged as uterus/uterus and 1 case was judged as uterus/ovary.The formula we established was thought to be useful to distinguish the origin of the cases in whom endometrioid type adenocarcinoma arises in both ovary and endometrium.