Objective To investigate the relationship between regulatory T cells in peripheral blood and pathological process, tumor burden and prognosis of patients with ovarian cancer.

Methods Sixty-four patients with ovarian cancer in the obstetrics and Gynecology department of Zhangjiakou First Hospital were selected (ovarian cancer group), and 80 patients with benign ovarian tumor at the same time were selected as benign group. Flow cytometry was used to detect the expression levels of CD4+CD25+Foxp3+/CD4+, CD8+CD28-/CD8+ and CD8+Foxp3+/CD8+ cells in two groups. Two groups were stratified and compared according to different pathological characteristics and detection results of circulating tumor cells (CTC) in peripheral blood. Logistic regression model was used to analyze the relationship between regulatory T cells and 3-year follow-up outcomes.

Results The expression levels of CD4+CD25+Foxp3+/CD4+, CD8+CD28-/CD8+ and CD8+Foxp3+/CD8+ cells in the peripheral blood of ovarian cancer group were significantly higher than those of benign group (P ＜ 0.05). The expression level of CD4+CD25+Foxp3+/CD4+cells in peripheral blood of ovarian cancer patients with FIGO stage (Ⅲ+Ⅳ), low differentiation, lymph node metastasis and CTC-positive was significantly higher than that of ovarian cancer patients with FIGO stage (Ⅰ+Ⅱ), high and medium differentiation, non-lymph node metastasis and CTC-negative (P ＜ 0.05). The expression level of CD8+CD28-/CD8+ cells in peripheral blood of ovarian cancer patients with FIGO stage (Ⅲ+Ⅳ), low differentiation and lymph node metastasis were significantly higher than that of ovarian cancer patients with FIGO stage (Ⅰ+Ⅱ), high and medium differentiation and non-lymph node metastasis (P ＜ 0.05). The expression level of CD8+Foxp3+/CD8+ cells in peripheral blood of ovarian cancer patients with FIGO stage (Ⅲ+Ⅳ) and low differentiation was significantly higher than that of ovarian cancer patients with FIGO stage (Ⅰ+Ⅱ) and high and medium differentiation (P ＜ 0.05). The results of Logistic regression model showed the expression levels of CD4+CD25+Foxp3+/CD4+, CD8+CD28-/CD8+ and CD8+Foxp3+/CD8+ increasing, FIGO stage (Ⅲ+Ⅳ), low differentiation and positive CTC were the independent risk factors of poor prognosis of ovarian cancer patients (P ＜ 0.05).

Conclusions The regulatory T cells in peripheral blood is related to the FIGO stage of ovarian cancer, degree of tumor differentiation and other tumor progression indicators. The expression of CD4+CD25+Foxp3+/CD4+ is related to the positive expression of CTC in patients' peripheral blood. The high expression of regulatory T cells in peripheral blood is an independent risk factor for poor prognostic outcome in patients with ovarian cancer.