Characteristics of study patients
A total of 156 patients were included in the analysis, and the median follow-up period was 82.2 months (range, 0.5 to 141.6 months). The baseline characteristics of these patients are summarized in Table 1. Their median age at diagnosis was 53 years (range, 15 to 87 years), and 69 (44.2%) patients were premenopausal. Regarding the FIGO stage of disease, 46 (29.5%), 19 (12.2%), 79 (50.6) and 12 (7.7%) were staged in I, II, III, Ⅳ respectively. The majority of patients had grade 3 disease (92, or 59.0%) with papillary serous histology (89, or 57.1%). Median CA-125 level was 275.3 kU/L (range, 5.3 to 10000 kU/L) in all patients, and 68 (43.6%) of them had lymph node metastasis. One hundred and thirty-seven patients (87.8%) underwent optimal cytoreductive surgery at initial exploration to residual disease less than 1 cm. Further descriptive data were shown in Table 1.
Cut-off determination of serum lipid and lipoproteins
ROC curves analysis showed that the optimal cutoff value of joint maximum sensitivity and specificity were for TC 4.86 mmol/L (AUC: 0.563, 95% CI: 0.468-0.658), 1.36 mmol/L for TG (AUC: 0.538, 95% CI: 0.447-0.629), 1.19 mmol/L for HDL-C (AUC: 0.624, 95% CI: 0.533-0.716), and 2.76 mmol/L for LDL-C (AUC: 0.597, 95% CI: 0.503-0.681), 1.51 g/L for apoA-Ⅰ (AUC: 0.554, 95% CI: 0.458-0.649), 1.01 g/L for apoB (AUC: 0.508, 95% CI: 0.413-0.602), respectively.
The prognostic impact of serum lipids on OS and PFS
In univariate analyses, early-stage (Ⅰ, Ⅱ), low grade tumors, non-serous histology, without lymph node metastasis, preoperative lower CA125 and optimal debulking (residual disease < 1 cm) were favorable prognostic factors for OS and PFS. Moreover, according to the recommended cutoff levels of preoperative serum lipids and lipoproteins, the preoperative higher TC, HDL-C, apoA-Ⅰ and lower LDL-C level were significantly associated with better OS and PFS (Tables 2 and 3).
In multivariate analyses, early-stage, without lymph node metastasis and optimal debulking remained as favorable prognostic factors for OS. Early-stage and optimal debulking predicted longer PFS. The HRs of OS were 2.005 (95% CI 1.057-3.805, p = 0.033) for advanced FIGO stage, 2.515 (95% CI 1.078-5.871, p = 0.033) for lymph node metastasis, and 3.913 (95% CI 1.925-7.956, p < 0.001) for suboptimal debulking, while the HRs of PFS were 1.939 (95% CI 1.209-3.111, p = 0.006) for advanced FIGO stage and 4.465 (95% CI 2.206-9.037, p < 0.001) for suboptimal debulking. Furthermore, the results revealed that preoperative higher LDL-C level was significantly associated with worse OS (HR 2.088, 95% CI 1.052-4.147, p = 0.035), whereas higher HDL-C level showed significant association with better PFS (HR 0.491, 95% CI 0.247-0.975, p = 0.042) (Tables 2 and 3).
Kaplan–Meier curves analyses of HDL-C and LDL-C
Kaplan–Meier curves with log-rank tests stratified by the cutoff value level of LDL-C and HDL-C were performed to assess the prognostic significance of the serum lipid profile in ovarian cancer. It demonstrated that the patients with high levels of HDL-C ( ≥ 1.19 mmol/L) had a better PFS compared with those with low levels of HDL-C ( < 1.19 mmol/L) (P = 0.001) (Fig. 1), whereas the patients with low levels of LDL-C ( < 2.76 mmol/L) had a better OS compared with those with high levels of LDL-C ( ≥ 2.76 mmol/L) (P = 0.028) (Fig. 2).