open access: Clear cell histology as a poor prognostic factor for advanced epithelial ovarian cancer: a single institutional case series through central pathologic review

Clear cell histology as a poor prognostic factor for advanced epithelial ovarian cancer: a single institutional case series through central pathologic review

"....  Clear cell carcinoma (CCC) of the ovary is a distinctive histological subtype characterized by clear cells growing in solid/tubular or glandular patterns as well as hobnail cells [8]. The proportion of clear cell carcinoma is relatively low in non-Japanese population, ranging from 3.7% to 12.1% [9-12]. However, in Japan, CCC accounted for 24.2% of all epithelial ovarian cancers, and the proportion has been increasing [13]. A report demonstrated the age-standardized rate (ASR) of CCC was significantly increased in not only older ages (>50), but also in younger ages (<50) [14]...."

"....According to recent reports comparing survival of CCC patients with that of SAC cases, there have been no significant difference of OS between those two histologic subtypes among stage I carcinomas of ovary demonstrated [9,11,15]. On the other hand, a study based on Surveillance, Epidemiology and End Results (SEER) database suggested that the patients with stage I CCC had poorer OS than patients with SAC [4]. However, other clinicopathologic factors such as peritoneal cytology, chemotherapy, and extent of surgical staging were not available in the data from SEER, although the independent poor prognostic factors of pT1M0 CCC were positive peritoneal cytology [23]. A subset analysis of a prospective phase III trial enrolling early-stage ovarian cancers revealed that there were no significant difference of PFS and OS between CCC and SAC [21]. Of note, Sugiyama et al. [15] suggested that OS of stage IC CCC was worse than that of stage IC SAC, although p-value did not reach a statistical significance. On the other hand, a consensus report from the first ovarian clear cell symposium suggested that early-stage CCC had a better outcome than that of high grade SAC of same stage; however, the results were not based on multivariate analyses [22]. The present study demonstrated that CCC histology was not a prognostic factor in stage I disease, and that peritoneal cytology was the only significant factor for PFS and OS. The results suggested by Sugiyama et al. [15] were in agreement of the present study, in that the status of peritoneal cytology was important for early-stage CCC ovarian cancers [23,24]. For the analysis of early-stage ovarian tumors, clinicopathologic factors including peritoneal cytology seem to be inevitable, as CCC showed chemo-resistant phenotype....."