In this study, the percentage of patients clinically thought to have stage I disease had the stage elevated to II-IV based on surgical staging pathologic findings was 9.2%, for the patients with FIGO stage IA and non-IA, the percentage was 0.0% and 12.6%, respectively.
As is shown in supplementary table 2, in previous studies, the percentage ranged from 12.8–31.8% [3, 5–7]. The percentage in our study in relatively lower than that in previous studies, the reason may be that, in our study, all the patients included were mucinous ovarian carcinoma, while the patients included in previous studies were ovarian epithelial carcinoma, the majority of those were serous carcinoma. As is mentioned before, high-grade serous were more frequently upstaged than other histological subtypes.
Interestingly, in our study, we found that, for apparent FIGO stage IA patients, no patient, of initial incomplete staging surgery, was found to have residual tumor confirmed by final pathological results of re-staging surgery, moreover, no patient, of whether restaging or one-step surgical staging surgery, was found to up-stage to FIGO stage II-IVB based on the final pathologic result.
To some extent, consistent with previous study, Peiretti M, et al found that surgical restaging seems to upstage a considerable number of ovarian granulosa cell tumors, mainly in the initial stage IC group of patients.
As we all know, to explore the possible risk factors of residual tumor during the initial incomplete staging surgery is of significance to clinical decision-making.
Unlike clear-cell and endometrioid carcinomas, which are frequently associated with marked adhesion to the surrounding tissues, due to endometriosis, mucinous carcinoma may be a possible candidate for cystectomy. However, in our study, after the multivariate analysis, we found that preservation of tumor-involved ovary, cystectomy, was related to the residual tumor. The reason why cystectomy was related to the residual tumor may be obvious, which could be explained by the hypothesis that preservation of tumor-involved ovary may have a risk of leaving residual tumor within the remaining ovarian tissue. This hypothesis was also been supported by a large retrospective study. In the above-mentioned study, the patients with cystectomy more frequently showed ovarian relapse than the patients with oophorectomy . Although oophorectomy is considered as an appropriate operation, cystectomy may be an unavoidable option when it is the only surgical procedure available to preserve fertility . In this situation, special care such as rigorous follow-up should be practiced to those patients with ovarian cystectomy.
There were a few studies which had investigated the possible risk factors of up-staging for epithelial ovarian carcinoma. And, as far as we know, this is the first study to explore the possible risk factors of up-staging specially for ovarian mucinous carcinoma, which may have greater significance. Interestingly, in our study, we found that the present of bilateral mucinous carcinomas was independent risk factors of up-staging to FIGO stage II-IVB.
Moreover, as we all know, to distinguish primary or metastatic mucinous carcinoma, continues a diagnostically challenging[11, 12]. It is thought that bilateral mucinous carcinomas may be an indicator for metastatic tumors . In the study of Seidman JD et al, among bilateral ovarian mucinous tumors, 6% (2/31)were primary and 94% (29/31) were metastatic, whereas, among unilateral ovarian mucinous tumors, 55% (10/19) were primary and 45% (9/19) were metastatic. Therefore, for the patients with bilateral mucinous carcinomas, complete staging surgery maintain greater significance which may alter treatment strategies.
Ovarian mucinous carcinomas are thought to grow from benign epithelium to borderline tumor to invasive carcinoma. And previous studies found the risk factors of borderline mucinous ovarian tumors evolving to carcinoma included residual disease after the initial surgery. Interestingly, in our study, we also found that the history of ovarian mucinous tumors was also an independent risk factor of up-staging to FIGO stage II-IVB. Therefore, the patients with ovarian mucinous benign or borderline tumor, no residual disease remaining maintains very important significance.
This study was limited by the inadequate large sample size and its retrospective nature, which could have possibly introduced some degree of bias. Despite these limitations, our study observed several important factors. The primary finding was regarding the percentage of up-staging to FIGO II-IVB for apparently FIGO stage I patients. The second important finding was regarding the potential risk factors for residual tumors and up-staging. The third finding was that for patients of apparent FIGO stage IA, the possibility of residual tumors or up-staging was low.
In conclusion, this study showed that the residual tumor was found in 17.9% of patients during incomplete staging surgery and the up-staging to II-IV stage in 9.2% of patients. The cystectomy was one independent risk factors for residual tumor, and both bilateral mucinous carcinomas and history of ovarian mucinous tumors were two independent risk factors for up-staging. For patients of apparent FIGO stage IA, the possibility of residual tumors and up-staging is relatively low. While for the patients with cystectomy, bilateral mucinous carcinomas, or history of ovarian mucinous tumors, complete staging surgery maintains great significance.