This retrospective real-world study aims to evaluate the efficacy and safety of anlotinib hydrochloride combined with immunotherapy as maintenance therapy following standard chemoimmunotherapy in extensive-stage small cell lung cancer (ES-SCLC).The study population consists of treatment-naïve ES-SCLC patients who did not progress after induction chemoimmunotherapy and subsequently received maintenance therapy with anlotinib plus immunotherapy. The primary objectives are progression-free survival (PFS)，overall survival (OS)

, and safety.

This multicenter study seeks to retrospectively analyze medical records (January 2022-December 2024) of extensive-stage small cell lung cancer (ES-SCLC) patients treated with anlotinib hydrochloride (12/10/8 mg doses) alongside immune maintenance therapy after first-line chemoimmunotherapy in real-world clinical settings. Key data points will encompass demographics, baseline disease characteristics, treatment regimens, efficacy outcomes (e.g., objective response rate, progression-free survival), and adverse event profiles. Eligible patients must have received anlotinib for ≥6 weeks and possess evaluable radiographic assessments. The primary objectives are to assess the clinical effectiveness and safety of this combination strategy in ES-SCLC.

Inclusion Criteria:

1. Male or female patients aged 18 years or older;
2. Histologically or cytologically confirmed extensive-stage small cell lung cancer (ES-SCLC) (per the Veterans Administration Lung Study Group [VALG] staging criteria);
3. Patients who previously received chemotherapy for limited-stage SCLC must have undergone curative-intent therapy (e.g., chemotherapy, radiotherapy, or chemoradiotherapy) and have a treatment-free interval of at least 6 months from the end of prior therapy (last chemotherapy cycle or radiotherapy) to the diagnosis of ES-SCLC;
4. At least one measurable target lesion (per RECIST version 1.1 criteria);
5. No disease progression after receiving 4-6 cycles of first-line chemoimmunotherapy induction therapy for ES-SCLC;
6. ECOG performance status: 0-2;
7. Life expectancy ≥3 months.

Exclusion Criteria:

1. Patients with limited-stage SCLC who previously received chemotherapy and underwent curative-intent therapy (e.g., chemotherapy, radiotherapy, or chemoradiotherapy) but experienced disease recurrence within 6 months after completion of prior therapy;
2. Patients with limited-stage SCLC who previously received immunotherapy agents (e.g., PD-1/PD-L1 inhibitors) or anti-angiogenic agents (e.g., Anlotinib, Apatinib, Bevacizumab);
3. Patients with extensive-stage small cell lung cancer (ES-SCLC) who developed disease progression during induction therapy with a standard chemoimmunotherapy regimen;
4. Active autoimmune diseases requiring systemic therapy (e.g., disease-modifying agents, corticosteroids, or immunosuppressants) within 2 years prior to the first dose;
5. Patients with coagulation dysfunction, defined as an International Normalized Ratio (INR) >1.5 or activated partial thromboplastin time (APTT) >1.5 × upper limit of normal (ULN), and/or those with a bleeding tendency;
6. Patients deemed by the inves.

Patients with treatment-naïve extensive-stage small cell lung cancer (ES-SCLC) who achieved non-progression after chemoimmunotherapy induction and received anlotinib plus immunotherapy maintenance therapy