European Journal of Gynaecological Oncology Eur. J. Gynaecol. Oncol. 2021 vol. 42(4), 782-787 ©2021 The Author(s). Published by IMR Press. Original Research Association of cancer-associated fbroblasts and survival in malignant ovarian neoplasms Ana Carolinne da Silva 1 , Millena Prata Jammal 1 , Renata Margarida Etchebehere 2 , Eddie Fernando Candido Murta 1 , Rosekeila Simões Nomelini 1, * 1 Department of Gynecology and Obstetrics/Research Institute of Oncology (IPON), Federal University of Triângulo Mineiro, 38025-440 Uberaba-MG, Brazil 2 Surgical Pathology Service, Federal University of Triângulo Mineiro, 38025-440 Uberaba-MG, Brazil *Correspondence: rosekeila@terra.com.br; rosekeila.nomelini@pesquisador.cnpq.br (Rosekeila Simões Nomelini) DOI:10.31083/j.ejgo4204118 This is an open access article under the CC BY 4.0 license (https://creativecommons.org/licenses/by/4.0/). Submitted: 18 April 2021 Revised: 1 June 2021 Accepted: 21 June 2021 Published: 15 August 2021 Objective: The aims of the study were to compare the stromal im- munostaining of smooth muscle alpha-actin (α-SMA) and fbroblast activation protein-α (FAP) between borderline ovarian tumors and epithelial ovarian cancer, and to evaluate their association in over- all survival (OS) and disease-free survival (DFS) in patients with ovar- ian cancer. Methods: Patients diagnosed with malignant (n = 28) and borderline ovarian tumors (n = 18) were evaluated. Immunohisto- chemical study of stromal α-SMA and FAP was carried out. The com- parison of immunostaining between borderline and malignant ovar- ian tumors was performed using Fisher's exact test. Survival was as- sessed by the Kaplan-Meier method and the log-rank test. Multi- variate analysis was performed by Cox regression. The differences were considered signifcant for p < 0.05. Results: Evaluating stro- mal FAP, stronger immunostaining (2 and 3) was more often found in epithelial ovarian cancer than in borderline ovarian tumors (p = 0.0331). There was no statistical signifcance in the assessment of α- SMA. Evaluating only patients with epithelial ovarian cancer, there was a higher OS in patients with stromal α-SMA immunostaining 3 (p = 0.017). There was no statistical signifcance when evaluating OS and DFS in patients with stromal FAP immunostaining, nor evaluat- ing DFS in patients with α-SMA stromal immunostaining 3. After multivariate analysis, patients with stromal α-SMA immunostain- ing 3 had higher OS compared to immunostaining 0, 1 or 2 [OR (95% CI) = 0.107 (0.018–0.649), p = 0.015]. Conclusion: Stronger FAP im- munostaining was more often found in epithelial ovarian cancer than in borderline ovarian tumors. In epithelial ovarian cancer, there was a higher OS in patients with stromal α-SMA immunostaining 3. Keywords Epithelial ovarian cancer; Borderline ovarian tumors; Smooth muscle alpha- actin; Fibroblast activation protein-α; Tumor microenvironment; Overall sur- vival 1. Introduction Epithelial ovarian cancer is a gynecological malignancy that has led to thousands of deaths among women worldwide. Risk factors that contribute to this disease are diverse, yet the most common genetic factor involves mutations in BRCA-1 and/or BRCA-2 genes [1]. Coburn et al.[2] have reported a stable incidence of ovarian cancer in various countries and re- gions of Europe, Asia, and North America. However, in the eastern and southern regions of Europe, an increased inci- dence of ovarian cancer has been observed, while a decreased incidence has been observed in northern Europe. Fibroblast activation protein-α (FAP) is a cellular surface antigen which is classified as a marker of cancer-associated fibroblasts (CAFs). FAP is a type II transmembrane protein and a serine protease of the prolyl oligopeptidase family [2– 4]. Expression of FAP is restricted to stromal fibroblasts and is induced in granulation and wound healing processes, fi- brosis, keloids, bone sarcomas, arthritis, and epithelial carci- nomas [4–7]. It is estimated that expression of FAP in the stromal compartment affects more than 90% of neoplasms of epithelial origin, and high expression of FAP has been related to poor prognosis in several types of carcinomas [4, 8–11]. Actin is a structural protein which functions in cellular motility and muscle contraction. Correspondingly, it is abun- dant in the cytoskeleton of eukaryotic cells and at least six isoforms have been identified [12, 13]. One of the best char- acterized isoforms of actin is smooth muscle alpha-actin (α- SMA) which is expressed in smooth muscle cells of the vascu- lature (e.g., myofibroblasts, blood vessels, and smooth muscle cells) [14]. It also exhibits significant functionality in fibroge- nesis [15–17]. Immunostaining of ovarian neoplasms for α- SMA alone has not produced significant results, yet staining of α-SMA in combination with other markers has provided more accurate results [18]. Furthermore, patterns and lev- els of α-SMA expression can be prognostic factors and have been related to overall survival (OS) [19]. Taken together, these results support further investigations of the roles and classification of surface marker expression by CAFs. The objectives of the present study were to compare stro- mal immunostaining of α-SMA and FAP between borderline ovarian tumors and ovarian epithelial malignancies, and to evaluate possible associations with OS and disease-free sur- vival (DFS) in patients with epithelial ovarian cancer.