The mortality of HGSOC ranks first among four main types of ovarian carcinomas: serous, endometrioid, clear-cell, and mucinous carcinomas [7–9]. Although some screening strategies have been developed to monitor the risk of HGSOC, such as CA125 and ultrasound, the survival rate of HGSOC remains low due to late detection [10]. Most researchers have focused on improving the accuracy of early diagnosis of HGSOC. In the present study, we have identified and validated that new index based on age, CA125 and ROMA2 has a good diagnostic performance with accurate sensitivity and specificity. The AUC of the new algorithm based on age, CA125 and ROMA2 was 0.933 in training cohort and 0.908 in validation cohort. The sensitivity and specificity of the new algorithm based on age, CA125 and ROMA2 were 89.66% and 82.44% in diagnosing HGSOC. This new index could be a new auxiliary diagnostic indicator in distinguishing HGSOC from non-HGSOC.
CA125 serves as a tumor biomarker in diagnosing ovarian cancer for decades with low sensitivity and specificity. Being first described by Bast and colleagues, CA125 has been studied thoroughly in the screening, diagnosis and prognosis of women gynecologic carcinomas [11]. It still does not have acceptable accuracy in population-based screening method to distinguish ovarian cancer patients [12–14]. There two main approaches to improve the accuracy of CA125 in diagnosing ovarian cancer. One approach is to modify the cutoff value. However, this approach cannot achieve both sensitivity and specificity [15]. In our results, the AUC of the CA125 in diagnosing HGSOC was 0.732. Previous studies demonstrated that the level of CA125 in 95% of health population was under 37U/ml, and the patients with benign lesions with median CA125 level above 20U/ml [16–18]. Thus, simply increasing the cutoff value of CA125 will reduce false positives, but at the same time increase false negatives. The other approach is developing multiple biomarker panels containing CA125. Anderson et al. performed immunoassays to identify the serum levels of CA125, HE4, mesothelin, decoy receptor 3, B7-H4, and spondin-2 for diagnosing of ovarian cancer and indicated that serum levels of CA125, mesothelin and HE4 might help in diagnosing ovarian cancer [19]. Yurkovetsky et al. analyzed the levels of serum biomarkers in health individuals and ovarian cancer patients. They selected a panel of CA125, HE4, CEA and VCAM-1 for screening epithelial ovarian cancer [20]. Russell and colleagues developed a diagnostic model of four putative proteins including CA125 that has the potential to diagnose epithelial ovarian cancer before current diagnosis for 1–2 years [21]. However, this clinical trial only included 49 epithelial ovarian cancer cases and 31 health controls, and the algorithm based on four putative proteins only classified 64% type II ovarian cancer at 1 year and 28% cases at 2 years.
Besides CA125, HE4 and CA724 were employed as routine serum biomarkers for the screening of ovarian carcinoma. HE4 is expressed in normal ovarian tissues at a low level and amplified in ovarian cancer, which could help to diagnose ovarian cancer [22, 23]. CA724 is glycoprotein that increases in various cancers, such as gastric, colon, breast and ovarian cancer. Because it is not affected by the menstrual cycle and pregnancy, CA724 has advantages than CA125 in diagnosing ovarian cancer [24, 25]. Some studies tried to screen ovarian carcinoma by combination of CA125, HE4 and CA724. Anastasi et al. analyzed the serum concentrations of CA125, HE4 and CA724 to discriminate ovarian cancer from ovarian endometrioma. They suggested that CA125, HE4, and CA724 are all increased in patients with epithelial ovarian carcinoma, while CA125 is elevated in patients with ovarian endometrioma [26]. The panel of these biomarkers yielded a sensitivity of 90% and a specificity of 70% in the diagnosis of epithelial ovarian carcinoma.
In order to improve sensitivity and specificity simultaneously, diagnostic algorithms are used in diagnosing ovarian cancer. First introduced by Jacobs et al, the Risk of Malignancy Index (RMI) was used for evaluating the probability of malignancies in pelvic mass [27]. In multiple studies, RMI showed compatible diagnostic performance with moderate sensitivity and specificity in distinguishing epithelial ovarian carcinoma from other lesions [28, 29]. Further, the ROMA algorithm was developed to assess the risk of epithelial ovarian malignancies [6]. But the sensitivity of ROMA was lower in premenopausal women than that in postmenopausal women. In the study cohort, we recalculated the diagnostic efficiencies of CA125, CA724, HE4, ROMA1 and ROMA2 by logistic regression model and found a new algorithm based on CA125, age, and ROMA2 has highest diagnostic performance in distinguish HGSOC from non-HGSOC lesions. Here, the sensitivity and specificity of new index were 89.66% and 82.44% in diagnosing HGSOC. This optimized the ROMA algorithm, making it more sensitive and specific in diagnosing ovarian cancer. What is more, we constructed a nomogram based on the risk factors identified by logistic regression analysis, leading to a more convenient way to diagnose ovarian cancer in clinical practice. However, it should be noted that this study was performed in single-center cohort and the number of cases was relatively small. Future studies should be performed to validate the applicability of this model.