Quad Shot Radiotherapy Combined With Tislelizumab and Platinum-Based Chemotherapy Before Surgery for Stage II-III Non-Small Cell Lung Cancer

Inclusion Criteria:

1. Age 18-75 years, either gender.
2. Histologically or cytologically confirmed, untreated stage II-IIIB non-small cell lung cancer (NSCLC) (including T3-4N2 IIIB, AJCC 9th edition). Baseline staging must include PET/CT (or chest + upper abdomen contrast-enhanced CT + whole body bone scan) + brain MRI. Stage III patients will be further subdivided into IIIA and IIIB per AJCC 9th edition for separate recording, evaluation, and analysis.
3. Evaluated as resectable by a multidisciplinary team including thoracic surgeons.
4. At least one evaluable target lesion per RECIST v1.1.
5. ECOG Performance Status 0-1.
6. Adequate major organ function: Neutrophils ≥ 1.5×10\^9/L; Platelets ≥ 100×10\^9/L; Hemoglobin \> 9.0 g/dL; Serum creatinine ≤ 1.5×ULN or Creatinine Clearance (CrCl) ≥ 40 mL/min; AST/ALT ≤ 3×ULN; Total bilirubin ≤ 1.5×ULN; INR/APTT within normal range; FEV1 ≥ 1.2L or \> 40% predicted.
7. Signed written informed consent prior to any study-related procedures.
8. Investigator judges that the patient is able to comply with the study protocol, willing and able to follow visit schedules, treatment plans, laboratory tests, and other study procedures.
9. Negative pregnancy test at screening (for women of childbearing potential). Subjects of childbearing potential (male and female) must agree to use effective contraception from screening until 180 days after the last dose.

Exclusion Criteria:

1. Known or suspected autoimmune disease (except vitiligo, Type I diabetes, or hypothyroidism requiring only hormone replacement therapy with no signs of recurrence).
2. Requires systemic corticosteroid therapy (\>10 mg/day prednisolone or equivalent) or other immunosuppressive drugs within 14 days prior to enrollment (inhaled or topical steroids, and physiological replacement doses of adrenal corticosteroids are allowed).
3. History of thoracic radiotherapy.
4. Active bleeding before treatment.
5. Severe heart, lung, liver, or kidney dysfunction, hematopoietic system disease, cachexia, or other conditions that make the patient unable to tolerate chemoradiotherapy.
6. History of diabetes for more than 10 years with unsatisfactory blood glucose control.
7. History of interstitial lung disease or non-infectious pneumonitis.
8. NSCLC patients with EGFR sensitizing mutations or ALK fusion genes.
9. Prior or concurrent other malignancies (except cured non-melanoma skin cancer and carcinoma in situ; or malignancies in complete remission for ≥ 2 years without requiring additional anti-tumor therapy during the study period).
10. Prior treatment with anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA-4, or other drugs targeting T-cell costimulatory or immune regulatory pathways.
11. Active hepatitis B (HBV DNA ≥ 2000 IU/mL or 10\^4 copies/mL) or hepatitis C (HCV antibody positive and HCV-RNA above the lower limit of detection).
12. HIV positive or diagnosed with acquired immunodeficiency syndrome (AIDS).
13. Received live vaccine within 4 weeks prior to the start of study treatment.
14. Known or suspected allergy to the study drugs or any related drugs in this trial.
15. Pregnant or breastfeeding women.
16. Investigator considers that the patient has other factors that may prevent completion of the study or affect subject safety or data collection.