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 the patients were in FIGO stage I (n = 347, 77.46%), with a few cases of stage II (n = 20, 4.46%), 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; 118 patients (26.34%) underwent staging surgery, whereas the rest underwent non-staging surgery. Abdominal/pelvic washings or ascites were collected prior to surgery for all patients, and positive involvement was identified in 27 patients (6.03%). Lymph node metastasis was detected in 21 of 113 patients who underwent lymphadenectomy. Appendix metastases were detected in 11 of 150 patients who underwent appendectomy. Omentum metastases were detected in 27 of 117 patients who underwent omentectomy. A total of 121 patients (27.01%) received adjuvant chemotherapy for lymph node metastasis, positive abdominal/pelvic washings, invasive implants, and/or other high-risk indicators.
Oncological outcomes of BOT patients
We carried out a survival analysis. The median follow-up for this study was 113 (range: 14–166) months. At the last follow-up, 42 (11.6%) patients experienced recurrence, 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 non-staging surgery (30/330, 9.09%) was lower than that in those underwent staging surgery (22/118, 18.64%), with the difference being statistically significant (P < 0.01). The results of univariate and multivariate analyses of DFS in all patients are shown in Table 2.
According to the univariate analysis, patients who underwent staging surgery had shorter DFS than those who underwent non-staging surgery. In addition, laparoscopy was strongly associated with improved DFS (HR = 0.292, 95% CI: 0.132–0.647, P = 0.002) compared to laparotomy. Other factors found to be associated with DFS were 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 FIGO stage (OR: 6.544, 95% CI: 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 significantly associated with DFS (P < 0.001, P = 0.014, P = 0.043, respectively) as per multivariate analysis; complete staging surgery was not associated with DFS (P = 0.600) as per multivariate analysis. There was no difference in DFS between patients who underwent FSS and radical surgery according to univariate and multivariate analyses.
Subgroup analysis showed that in patients who underwent staging surgery, there was no difference in DFS between those who underwent laparotomy or laparoscopy (P = 0.349). Among patients who underwent non-staging surgery, the DFS was longer for patients who underwent laparoscopy than for 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 (Table 3).
Univariate analysis with patients who underwent FSS showed that patients who underwent staging surgery had shorter DFS than those who underwent non-staging procedures (OR: 4.290, 95% CI: 1.979–9.298, P < 0.001). DFS was better among patients who underwent laparoscopy (OR: 0.332, 95% CI: 0.135–0.820, P = 0.017) than among those who underwent laparotomy. In addition, patients who underwent salpingo-oophorectomy had longer DFS than those who underwent a cystectomy 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 multivariate analysis, there was no difference in DFS between patients who underwent staging and non-staging surgery (P = 0.358). There was no difference in DFS 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 the 270 patients who underwent FSS, 252 patients had attempted to conceive and 92 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, at a statistically significant (P < 0.001) level. Of the 30 patients who underwent staging surgery, 13 patients succeeded in conceiving, whereas 79 of 203 patients who underwent non-staging surgery succeeded in conceiving, but these differences were not statistically significant (P > 0.05). There was no difference between patients who underwent laparotomy or laparoscopy. Similarly, among patients who underwent salpingo-oophorectomy or cystectomy, there was no difference in the pregnancy rates (P > 0.05).