In India, more than 5 lakh deaths are registered due to lung cancer every year. Recently, PD- L1 (Programmed death ligand 1) has emerged as an important cancer biomarker and target for immunotherapy. With the help of PD- L1, it can reduce the growth of a tumour in presence of immune cells.

According to you, in which stages of lung cancer, PD- L1 can be used? What is the exact role of PD-L1 in immunotherapy for small cell and non-small cell lung cancer?