Recurrence factors of stage I ovarian clear cell carcinoma.

e16577 Background: Ovarian clear cell carcinoma (CCC) is relatively resistant to anticancer drugs, and its prognosis is poor even in stage I compared to other histologic types. Generally, it is indicated for postoperative chemotherapy, but many points remain unclear with regard to recurrence factors. We investigated recurrence factors of stage I CCC. Methods: Between January 1988 and December 2011, patients diagnosed with stage I CCC by staging laparotomy were registered. Age, stage, tumor diameter, presence or absence of endometriosis, number of excised lymph nodes, and presence or absence of postoperative chemotherapy were investigated, and their associations with recurrence were retrospectively investigated. We diagnosed recurrence by image or pathology. The cut-off value of the number of excised lymph nodes to predict recurrence was calculated from the receiver operating characteristic curve. Cox regression analysis was used to determine the risk factors for recurrence with hazard ratios (HR). Results: 59 patients were enrolled. The median age was 52 (31-77) years old. 15 patients had stage IA, 25 IC(1), 5 IC(2), 14 IC(3). The median tumor diameter was 12 (5-28) cm, 38 patients (67%) were complicated by endometriosis, and postoperative chemotherapy was performed in 46 (78%). The median number of excised lymph nodes was 54 (6-135), and the cut-off value to predict recurrence was 34. Recurrence occurred in 18 patients (31%). On univariate analysis, IC(2,3) (vs. IA+IC(1); p = 0.007) and the number of excised lymph nodes being 34 or lower (vs. 35 or greater; p = 0.004) were extracted as significant recurrence factors. The HR of these 2 factors on multivariate analysis were 3.28 [95% confidence interval (CI): 1.28-8.45] and 3.57 [95% CI: 1.37-9.30], respectively. Conclusions: Stage and number of excised lymph nodes were independent recurrence factors of stage I CCC. Staging laparotomy with sufficient lymph node dissection could lead to recurrence prevention as well as accurate staging.