Patient characteristics
A total of 448 patients with BOT were enrolled in this study. The demographics and clinicopathological characteristics are shown in Table 1.
The median age at diagnosis was 37.1 years (range: 11–82 years). The majority of patients were of FIGO stage I (n=347, 77.46%), whereas a few cases were of stage II (n=20, 4.46%), and the remaining were of stage III (n=74, 16.52%) and stage IV (n=7, 1.56%). The most common pathological type of BOT was serous (n=258, 57.59%), followed by mucinous (n=150, 33.48%), serous/mucinous (n=32, 7.14%), and endometrioid (n=8, 1.79%). Notably, most patients had unilateral lesions (n=352, 78.57%), whereas 96 (21.43%) patients had bilateral lesions. Among the patients enrolled, 81 (18.08%) had micropapillary lesions, 88 (19.64%) had microinvasion lesions, and 25 (5.58%) had carcinogenesis lesions.
Regarding surgical approach, 298 patients (66.52%) underwent laparotomy and 150 patients (33.48%) underwent laparoscopy. A total of 118 cases (26.34%) underwent complete staging surgery, whereas the rest underwent incomplete staging or unstaged surgery. Abdominal/pelvic washings or ascites were collected prior to the surgeries of all patients, and positive involvement was identified in 27 patients (6.03%). Lymph node metastasis was detected in 21 patients among those who had lymphadenectomy (n=113). Appendix metastases were detected in 11 patients among those who underwent appendectomy (n=150). Omentum metastases were detected in 27 patients among those who underwent omentectomy (n=117). A total of 121 patients (27.01%) received adjuvant chemotherapy due to lymph node metastasis, positive abdominal/pelvic washings, invasive implants, and/or other high-risk indicators.
Oncological outcomes in patients with BOT
Survival analysis was performed; the median follow-up for this study was 113 (range: 14–166 ) months. At the last follow-up, 42 (11.6%) patients experienced recurrences, with a mean recurrence interval of 80.2 months and 4 (0.9%) disease-specific deaths were observed. The recurrence rate in patients who underwent incomplete staging/unstaged surgery (30/330, 9.09%) was lower than that in those receiving complete staging surgery (22/118, 18.64%), which was statistically significant (P<0.01). Results of univariate and multivariate analyses of DFS in all patients are shown in Table 2.
According to the univariate analysis, patients who received complete staging surgery had shorter DFS than those who underwent incomplete staging or unstaged surgery. In addition, laparoscopy was more associated with improved DFS (HR=0.292, 95% CI: 0.132–0.647, P=0.002) compared to laparotomy. Other factors were found to be associated with DFS, including FIGO stage, histology, lesion location, microinvasion, adjuvant chemotherapy, ascites/pelvic washings, cancer antigen (CA)-125 level, appendectomy, and invasive implants (all P<0.01). Micropapillary and carcinogenic lesions were not associated with DFS (P>0.05).
Although several factors were found to be associated with DFS by univariate analysis, only three of them, including FIGO stage (OR: 6.544, 95%: 2.137–20.041), positive ascites/pelvic washings (OR: 3.259, 95% CI: 1.202–8.835), and surgical approach (OR: 0.319, 95% CI: 0.128–0.793), were identified as factors significantly associated with DFS (P<0.001, P=0.014, P=0.043, respectively) by multivariate analysis. However, complete staging surgery was not associated with DFS (P=0.600) according to the multivariate analysis. There was no difference in DFS found between patients who underwent either FSS or radical surgery by both univariate and multivariate analyses.
Subgroup analysis showed that, in patients who underwent complete staging surgery, there was no difference in DFS between those who received either laparotomy or laparoscopy (p=0.349). In patients who underwent incomplete staging/unstaged surgery, the DFS in patients who underwent laparoscopy was longer than in those who underwent laparotomy (P=0.011; Supplementary Table 1).
Oncological outcomes in patients with BOT after FSS
Among the patients enrolled, 270 patients underwent FSS. Of these, 32 patients (11.8%) experienced recurrence. To explore the potential risk factors associated with improved DFS in patients who underwent FSS, univariate and multivariate analyses were performed, shown in Table 3.
Univariate analysis in patients with FSS revealed that patients who underwent complete staging surgery had shorter DFS than those who underwent incomplete staging or unstaged procedures (OR: 4.290, 95% CI: 1.979–9.298, P<0.001). When compared to those who underwent laparotomy, DFS in patients who underwent laparoscopy was improved (OR: 0.332, 95% CI: 0.135–0.820, P=0.017). In addition, patients who underwent salpingo-oophorectomy had longer DFS than those who underwent a cystectomy-included procedure (OR: 0.230, 95% CI: 0.168–0.867, P=0.021). Other factors were also associated with DFS in patients who underwent FSS, including FIGO stage, histology, lesion location, microinvasion, adjuvant chemotherapy, positive ascites/pelvic washings, appendectomy, and invasive implants (P<0.05).
In the multivariate analysis, there was no difference in DFS between patients who underwent complete or incomplete/unstaged surgery (P=0.358). No difference in DFS was found between patients with different histological types. Early FIGO stage (OR: 11.586, 95% CI: 4.535–29.602), unilateral lesions (OR: 2.581, 95% CI: 1.061–6.283), laparoscopy (OR: 0.367, 95% CI: 0.148–0.913), salpingo-oophorectomy (OR: 0.367, 95% CI: 0.148–0.913), and no invasive implants (OR: 4.832, 95% CI: 1.663–14.037) were independent factors for improved DFS (p<0.05).
Reproductive outcomes in patients with BOT after FFS
At the last follow-up, of 270 patients who underwent FSS, 252 patients had attempted to conceive and 92 had achieved pregnancy. The correlation between clinicopathological characteristics and reproductive outcome is shown in Table 4. The pregnancy rate in patients aged <35 years was higher than those aged ≧35, and was statistically significant (P<0.001). Of 30 patients who underwent complete staging surgery, 13 patients succeeded in conceiving, whereas 79 of 203 patients who underwent incomplete/unstaged surgery succeeded in conceiving, but these differences were not statistically significant (P>0.05). There was no difference between patients who received either laparotomy or laparoscopy. Similarly, in patients who underwent salpingo-oophorectomy or cystectomy, there was no difference in pregnancy rate (P>0.05).