The correlation between chemotherapy combined with immunotherapy and the evolution of intestinal flora in small cell lung cancer

Interventions: A:Naught;B:Live Bacillus licheniformis capsule;C:Live Combined Bacillus Subtilis and Enterocoocus Faecium Enteric-coated Capsules;D:Triple Viable Capsules Dissolving at Intestines Primary outcome(s): Overall survival Study Design: Parallel