This is a single-arm, real-world study in Chinese patients with extensive stage small cell lung cancer. The purpose of this study was to evaluate Trilaciclib's protection against chemotherapy-induced bone marrow suppression, the safety and the impact on the antitumor effects of the combination with chemotherapy in Chinese patients with ES-SCLC in the real world. Patients with ES-SCLC who already use or plan to use Trilaciclib will be invited to participate in the study. Data were collected from 28 days prior to initial chemotherapy (platinum/etoposide or topotecan systemic chemotherapy) after patients signed informed consent until patients died, dropped out of the study, lost to follow-up, informed withdrawal, or study termination. The end time of the study was defined as withdrawal of information, loss of follow-up or death of all enrolled patients, or 12 months after the last patient was enrolled, whichever happened earlier.

Inclusion Criteria:

1. Voluntarily participate and sign informed consent;
2. must be at least 18 years when fisrt dose of Trilaciclib, regardless of gender:
3. Patients with extensive small-cell lung cancer confirmed by histology or cytology
4. Patients suitable for Trilaciclib combined with platinum/etoposide or Trilaciclib combined with topotecan treatment

Exclusion Criteria:

1. Patient is currently participating in other Interventional clinical studies;
2. Patients received systemic chemotherapy other than the regimens recommended in inclusion criteria 4 During Trilaciclib treatment.