Immune checkpoint inhibitors (anti PD-1 or anti PD-L1) versus chemotherapy for second- or third-line treatment of metastatic non-small cell lung cancer

To evaluate the effectiveness and safety of immune checkpoint inhibitors (anti PD-1 or anti PD-L1) compared with standard chemotherapy for second- or third-line treatment of metastatic non-small cell lung cancer (NSCLC).

This is a protocol.