The possible existence of occult metastasis in patients with ovarian clear-cell carcinoma who underwent complete resection without any residual tumours.

The objective of this study was to estimate the frequency of possible occult metastasis through long-term survival analyses in patients with clear cell carcinoma (CCC) who had undergone complete resection. During the period of 1990-2015, 799 patients with stage I-IV CCC were identified in the TOTSG database. Of these, a total of 528 patients without a residual tumor were enrolled in the study and classified into four groups: Group 1: FIGO stage IA-IB (N=104), Group 2: FIGO stage IC1 (N=170), Group 3: FIGO stage IC2/IC3 (N=98), and Group 4: FIGO stage II-III (no residual tumor: N=156). Cumulative incidences of recurrence (CIR) and death (CID) were examined. The median age was 54, ranging from 29-87. The 5-year CIR / CID of each group were as follows: Group 1 (7.3% / 3.8%), Group 2 (14.3% / 10.2%), Group 3 (37.7% / 18.4%), and Group 4 (46.5% / 33.8%), respectively { P <0.0001 (recurrence) / P <0.0001 (death)}. Furthermore, confining analysis to relapsed patients, 1-, 2-, and 3-year CID after recurrence were 41.5, 60.9, and 73.9, respectively. Confining analyses to patients with sufficient information about adjuvant chemotherapy, the 5-year CIR / CID of stage IA-IC1 patients with or without chemotherapy were as follows: recurrence {13.0% (yes) / 9.6% (no)}, death {9.3% (yes) / 4.2% (no)}, respectively { P =0.947 (CIR) / P =0.224 (CID)}. CCC patients staged greater than IC2/ IC3 show a marked risk of mortality, even after complete surgical resection.
Competing Interests: CONFLICTS OF INTEREST All authors declare that there are no conflicts of interest.