Kakimoto et al. Diagnostic Pathology (2021) 16:28 https://doi.org/10.1186/s13000-021-01093-4 RESEARCH Open Access Significance of mesothelin and CA125 expression in endometrial carcinoma: a retrospective analysis Soichiro Kakimoto1, Morikazu Miyamoto1* , Takahiro Einama2, Yasuhiro Takihata2, Hiroko Matsuura1, Hideki Iwahashi1, Hiroki Ishibashi1, Takahiro Sakamoto1, Taira Hada1, Jin Suminokura1, Tsubasa Ito1, Rie Suzuki1, Ayako Suzuki1,3 and Masashi Takano1 Abstract Background: This study aimed to investigate the association between clinicopathologic factors, mesothelin, and cancer antigen (CA) 125 in endometrial carcinoma. Methods: Between 1989 and 2017, patients with endometrial carcinoma who underwent total hysterectomy and bilateral salpingo-oophorectomy at our hospital were identified. The association between either or both immunochemical expression of mesothelin and CA125 and clinicopathological features were retrospectively examined. Results: Among 485 patients, 171 were positive for mesothelin, 368 were positive for CA125, and 167 were positive for mesothelin and CA125. The expression of mesothelin and CA125 was positively correlated (p < 0.01). More patients with mesothelin expression showed myometrial invasion of more than 50% (p = 0.028) and positive lymphovascular invasion (p = 0.027). Similarly, more patients with co-expression of mesothelin and CA125 had myometrial invasion of more than 50% (p = 0.016) and positive lymphovascular invasion (p = 0.02). Patients with mesothelin expression and co-expression of mesothelin and CA125 demonstrated worse progression-free survival (PFS) and overall survival (OS). In the multivariate analysis, mesothelin expression and co-expression were poor prognostic factors for PFS (mesothelin expression: hazard ratio [HR] = 2.14, p < 0.01; co-expression: HR = 2.19, p < 0.01) and OS (mesothelin expression: HR = 2.18, p < 0.01; co-expression: HR = 2.22, p < 0.01). Conclusions: Mesothelin expression and co-expression might be associated with tumor aggressiveness and poor prognosis in patients with endometrial carcinoma. Persons with mesothelin-expressing endometrial cancers present a particularly high medical unmet need. Keywords: Endometrial carcinoma, Mesothelin, CA125, Prognosis, Co-expression, Gynecologic carcinoma Background EC are surgery and adjuvant therapy including chemo- The incidence of endometrial carcinoma (EC) has grad- therapy and radiotherapy according to the recurrent risk ually increased, and ECs is one of the major types of gy- factor [2]. Due to the advances in treatment, the progno- necologic carcinomas [1]. The standard treatments for sis of these patients has dramatically improved, but those with advanced disease stage of aggressive histological * Correspondence: [email protected] subtypes such as serous carcinoma showed worse prog- 1Department of Obstetrics and Gynecology, National Defense Medical nosis [3]. College Hospital, Tokorozawa, Saitama 359-8513, Japan Full list of author information is available at the end of the article © The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Kakimoto et al. Diagnostic Pathology (2021) 16:28 Page 2 of 10 Mesothelin, a 40-kDa protein, is normally expressed in 3+, ≥50% of cells stained in the entire carcinoma tissue. mesothelial cells of the pleural cavity, peritoneal cavity, The staining intensity score was defined as follows: 0, no and peritoneum [4, 5]. Furthermore, mesothelin has a tumor cells stained in the entire carcinoma tissue; 1+, strong affinity to cancer antigen 125 (CA125) with N- incomplete membrane staining and/or faint or barely linked glycans [6]. Several studies reported that co- perceptible cytoplasmic staining detected; and 2+, entire expression of mesothelin and CA125 correlated with ag- circumference of the cell membrane stained and/or gressive features of tumors and poor prognosis of several moderate to strong cytoplasmic staining. A tumor pro- carcinomas such as ovarian carcinomas [7–16]. How- portion score of 3+ and/or a staining intensity score of ever, only a few studies have investigated the association 2+ was considered positive for mesothelin (Fig. 1a) or between mesothelin and CA125 expression in ECs [17– CA125 expression (Fig. 1b). On the contrary, other cases 20]. Therefore, we considered the need to study the rela- were considered negative for mesothelin (Fig. 1c) or tionship between these expressions and clinicopathologi- CA125 expression (Fig. 1d). Additionally, presence of cal features. both mesothelin-positive and CA125 cells was consid- Herein, this study aimed to evaluate the correlation ered as co-expression. Two observers evaluated immu- between the clinicopathological factors and either the noreactivity without prior information of clinical data. In expression of mesothelin or CA125 or co-expression of the interpretation of immunohistochemistry, any dis- these biomarkers in endometrial carcinoma. crepancies between 2 observers were resolved through discussion over a multiviewer microscope. Methods Patients Statistical analysis Patients with endometrial carcinoma who underwent Histological subtypes were classified into four types: total hysterectomy and bilateral salpingo-oophorectomy grade 1, endometrioid carcinoma; grade 2, endometrioid in our hospital between 1989 and 2017 were identified. carcinoma; grade 3, endometrioid carcinoma, and other All patients were re-evaluated pathologically according carcinomas including serous carcinoma, clear cell car- to the 2020 World Health Organization criteria [21]. cinoma, carcinosarcoma, and mixed carcinoma. The χ2 Those with grades 1, 2, and 3 endometrioid carcinoma, test and Fisher’s exact test were used to confirm the cor- serous carcinoma, clear cell carcinoma, carcinosarcoma, relation between the clinicopathological data and and mixed carcinoma were included in this study. Pa- mesothelin and CA125 expression. Progression-free sur- tients with other histological types, complicated with vival (PFS) and overall survival (OS) curves were drawn other carcinomas, and lack of either clinical information using the Kaplan-Meier method. The differences be- or surgical specimens were excluded. All patients quali- tween the survival curves were analyzed using the Cox fied in the period were included. The clinicopathological proportional hazard test. In the statistical analysis, all p- factors were obtained from the medical records. values of < 0.05 were considered significant. The soft- ware JMP® 14.0 (SAS Institution Inc., Cary, NC, USA) Immunohistochemical analysis was used to perform all statistical analyses. Four-hundred and eighty-five formalin-fixed paraffin- embedded tissues were used for tissue microarray Results (TMA). All slides were stained immunohistochemically The details of the tumor proportion and intensity scores as previously reported [20]; anti-mesothelin (clone 5B2 are shown in Table 1. Two-hundred and sixteen patients diluted 1:50 Leica: NCL-L-MESO) and anti-CA125 (45%) showed absence of mesothelin expression. A total (clone M11 diluted 1:50 DAKO:M3520) antibodies were of 68 (14%) patients had a tumor proportion score of 3+, used under the same conditions. while 166 had a staining intensity score of 2+ on mesothelin staining Among the 485 patients, 171 (35%) Immunohistochemical evaluation were positive for mesothelin expression. Similarly, 56 pa- The evaluation methods used were those described in tients (11%) showed absence of CA125 expression. Two prior literature and our previous studies [10, 20]. The hundred seventy (56%) patients had a tumor proportion expression of mesothelin and CA125 was determined by score of 3+, while 364 (75%) had a staining intensity evaluating the tumor proportion score and staining in- score of 2+ on CA125 staining. Moreover, 368 (75%) pa- tensity score. The tumor proportion score, defined as tients showed were positive for CA 125 expression, while the percentage of mesothelin- or CA125-positive cells in 167 (34%) demonstrated co-expression of mesothelin carcinoma tissues, was as follows:0, no tumor cells and CA 125. The relationship between the histological stained in the entire carcinoma tissue; 1+, ≥1 to < 10% of subtypes and expression is shown in Table 2. Only a few cells stained in the entire carcinoma tissue; 2+, ≥10 to < patients had grade 1 endometrioid carcinoma and more 50% of cells stained in the entire carcinoma tissue; and had other types of carcinomas in the groups with Kakimoto et al. Diagnostic Pathology (2021) 16:28 Page 3 of 10 Fig. 1 (See legend on next