Abstract: A method for predicting immunotherapy response of a subject having cancer includes the following steps. A peripheral blood sample is obtained from the subject having cancer before or after receiving the immunotherapy. The number of immune cells in the peripheral blood sample of the subject having cancer is detected. The number of immune cells and a first cut-off value/or a second cut-off value are compared to indicate whether the subject having cancer benefits from the immunotherapy. The first cut-off value/or the second cut-off value is determined by the following steps: a statistical analysis of a correlation between the number of immune cells in a group of subjects having cancer and an expected risk of disease progression in the group of subjects having cancer is performed, and then a statistically significant value used to define the correlation is obtained.

Abstract: Disclosed is a method for identifying a subject at risk of developing a recurrent or metastatic cancer, comprising detecting PD-L1+ circulating tumor cells in a blood sample, a tissue fluid sample or a specimen of the subject. Also disclosed is method for treating a cancer comprising identifying a subject having one ore more PD-L1+ circulating tumor cells by detecting PD-L1+ circulating tumor cells in a blood sample, a tissue fluid sample or a specimen of the subject, and administering a treatment to the subject.