ALK and Pleural effusion: The present study aimed to find out the expression of PD-L1 in patients with non-small cell lung cancer (NSCLC) from Kerala and its relationship to different clinical and pathological parameters, including gender, smoking status, metastasis, pleural effusion, and histopathological subtypes, along with gene mutations like epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) [7].