Mast cells and M2 macrophages in ovarian cancer

The objectives of this study were to investigate the immunohistochemical expression of markers of mast cells and M2 macrophages in benign and malignant ovarian neoplasms and to examine the prognostic value of this expression in ovarian cancer. The study was performed with samples from 32 patients, divided into benign (n = 16) and malignant (n = 16) neoplasm groups. Samples obtained by surgical resection were submitted to immunohistochemical analysis. Higher proportions of M2 macrophages (p = .041) and mast cells (p = .0054) were present in malignant than benign ovarian neoplasms. Histological grade 2/3 was related to higher proportions of M2 macrophages compared with grade 1 (p = .0102). Stages II-IV were also related to higher proportions of M2 macrophages (p = .0102). Logistic regression revealed that M2 macrophages predicted malignancy [odds ratio (OR) = 1.017; 95% confidence interval (CI), 1.003-1.037; p = .017], but that mastocytes had greater predictive value for this outcome (OR = 1.127; 95% CI, 1.018-1.105; p = .013). M2 macrophages predicted more advanced histological grades (OR = 1.060; 95% CI, 1.010-1.218; p = .003). The proportions of M2 macrophages and mast cells were greater in malignant than in benign ovarian neoplasms. Larger proportions of cells expressing M2 macrophages were related to more advanced histological grades and disease stages, and thus to worse prognoses for ovarian cancer.Impact StatementWhat is already known on this subject? Concentrations of mast cells and M2 macrophages have been observed in several tumour types, but their significance remains uncertain.What do the results of this study add? The proportions of M2 macrophages and mast cells were greater in malignant than in benign ovarian neoplasms. Larger proportions of cells expressing M2 macrophages were related to higher histological grades and more advanced stages of the disease.What are the implications of these findings for clinical practice and/or further research? Larger proportions of cells expressing M2 macrophages were related to worse prognoses for malignant ovarian neoplasia. The discovery of new prognostic factors in ovarian cancer may be the target of studies on new treatments and immunotherapies for this disease. In addition, it can help guide the oncologist towards more aggressive treatments for patients with worse prognostic factors.