Anaemia is a risk factor for poor chemotherapy outcomes.28 Nadir Hb post-chemotherapy and survival in NSCLC patients without baseline anaemia are significantly associated.29 However, a large-scale retrospective study found no association between anaemia and OS for LD-SCLC.30 In the current study, the subgroup analysis indicates that anaemia is a significant prognostic factor for poorer OS only in patients with ED-SCLC. Here, GSTM1 is linked to small cell lung carcinoma.