Role of Alpha-Smooth Muscle Actin and Fibroblast Activation Protein Alpha in Ovarian Neoplasms

Background/Aims: Studies show that tumor growth is not just determined by the presence of malignant cells, since interactions between cancer cells and stromal microenvironment have important impacts on the cancer growth and progression. Cancer-associated fibroblasts play a prominent role in this process. The aims of the study were to investigate 2 cancer-associated fibroblasts markers, alpha-smooth muscle actin (α-SMA), and fibroblast activation protein alpha (FAP) in the stromal microenvironment of benign and malignant ovarian epithelial neoplasms, and to relate their tissue expression with prognostic factors in ovarian cancer. Methods: α-SMA and FAP were evaluated by immunohistochemistry in malignant ( n = 28) and benign ( n = 28) ovarian neoplasms. Fisher’s exact test was used with a significance level lower than 0.05. Results: FAP immunostaining was stronger in ovarian cancer when compared to benign neoplasms ( p = 0.0366). There was no significant difference in relation to α-SMA expression between malignant and benign ovarian neoplasms as well as prognostic factors. In ovarian cancer, FAP stainings 2/3 was significantly related to histological grades 2 and 3 ( p = 0.0183). Conclusion: FAP immunostaining is more intense in malignant neoplasms than in benign ovarian neoplasms, as well as in moderately differentiated and undifferentiated ovarian carcinomas compared to well-differentiated neoplasms, thus indicating that it can be used as a marker of worse prognosis.