This is a multi-center, retrospective + prospective, real-world observational study. It aims to investigate, through a relatively large sample size, the effectiveness and safety of different treatment approaches for preventing and managing neutropenia in cancer patients after chemotherapy. Additionally, it seeks to observe the impact of different treatment management models on the quality of life of cancer patients undergoing chemotherapy, so as to provide real-world evidence for selecting different treatment strategies for cancer patients after chemotherapy in the future.