Effect of exemestane endocrine therapy for hormone-receptor-positive breast cancer patients with varying levels of ctDNA.

Purpose: To determine the effectiveness of exemestane in the treatment of hormone receptor (HR)- positive breast cancer patients with different levels of circulating tumor DNA (ctDNA). Methods: HR-positive breast cancer patients admitted at the Oncology Department of Harbin Medical University Cancer Hospital, Harbin, China from January 2017 to January 2019 were selected as subjects. They were given endocrine therapy with exemestane, and subjected to plasma ctDNA screening. The expression levels of ctDNA, levels of factors that influence ctDNA expression, ctDNA expression levels before and after treatment, clinical efficacy of treatment, long-term prognosis, and factors that influence prognosis of the disease, were determined. Results: There were 57 ctDNA-positive patients and 23 ctDNA-negative patients, accounting for 71.25 % positive ctDNA expression. Post-treatment, 32 patients were ctDNA-positive, while 48 patients were ctDNA-negative. There were significant differences in age distribution, cases of lymph node metastasis, and levels of CEA, CA125 and CA153 between ctDNA-negative and ctDNA-positive groups (p < 0.05). The ORR of ctDNA-negative group was significantly higher than that of ctDNA-positive group (X2 = 6.841; p = 0.009). Decrease (Δ) in the levels of CEA, CA125 and CA153 in the ctDNA-negative group was significantly higher than those in control group (p < 0.001). The overall survival time of ctDNAnegative group was significantly better than that of ctDNA-positive group. Conclusion: ctDNA mutations in HR-positive breast cancer patients correlated with clinical outcomes of neoadjuvant treatment with exemestane. The treatment resulted in marked reduction in number of ctDNA-positive patients. [ABSTRACT FROM AUTHOR]