Patients were divided into two groups according to ctDNA HER2 amplification status by dPCR method. Group A consisted of patients with positive HER2 amplification at the time of enrollment. Plasma HER2 amplification status was measured by dPCR during dynamic monitoring. GroupB consists of patients with negative HER2 amplification when enrolled. Plasma samples were collected before treatment and breast cancer hotspot mutations were detected with NGS, According to the NGS test results, patient's specific mutations were analyzed and selected, which and plasma HER2 amplification status were measured by dPCR during dynamic monitoring.~The study was designed to investigate the relationship between plasma HER2 amplification or specific mutations abundance and imaging assessment in patients with recurrent or metastatic breast cancer. And also to investigate the proportion of predicting in advance the treatment efficacy of recurrent or metastatic breast cancer by plasma HER2 ctDNA, as well as the median time difference between predicted clinical efficacy by changes in abundance of plasma HER2 amplification specific mutations and medical imaging evaluation in patients.~The study only focus on ctDNA detection and does not involve any interventions.
This was a prospective, single-center clinical study. The study was designed to investigate the relationship between plasma HER2 amplification or specific mutations abundance and clinical response in patients with recurrent or metastatic breast cancer.