Clinical characteristics and serum CA19‐9 combined with HE4 are valuable in diagnosing endometriosis‐associated ovarian cancer

Abstract Objective Endometriosis‐associated ovarian cancer (EAOC) is difficult to diagnose because of its low incidence, uncertain risk factors, and the absence of effective markers. This study aimed to investigate the clinical characteristics of EAOC and identify useful serological markers. Methods We retrospectively studied the clinical characteristics of patients with EAOC and ovarian endometriosis, obtained between January 1, 2011 and October 31, 2021. Univariate and multivariate logistic regression analyses were used to explore the relationship between clinical characteristics and EAOC. Receiver operating characteristic curves were applied to access the diagnostic value of serological markers in EAOC. Results In total, the clinical characteristics of 220 patients were obtained; 44 with EAOC and 176 with ovarian endometriosis. EAOC patients were older (46.20 vs. 36.26 years, P < 0.001) and had larger tumors (9.10 vs. 6.73 cm, P = 0.003) together with higher CA19‐9 (21.44 vs. 4.72 U/mL, P < 0.001) and HE4 levels (62.35 vs. 44.19 pmol/L, P < 0.001) when compared with ovarian endometriosis patients. Multivariate analysis showed that HE4 greater than 59.7 pmol/L, CA19‐9 greater than 8.5 U/mL, age 42 years or older, and tumor length 9.2 cm or longer were independent risk factors for EAOC. Significantly, CA19‐9 combined with HE4 had high sensitivity (72.73%) and specificity (78.41%) in diagnosing EAOC. Conclusion Age over 42 years, large ovarian tumor, serum CA19‐9 and HE4 are valuable in the diagnosis of EAOC.