Primary Tumor Resection Plus Osimertinib in Advanced EGFR-mutant Non-small Cell Lung Cancer

Prior treatment

• Immunodeficiency: history of primary immunodeficiency disorders, or prior allogeneic organ or bone marrow transplantation.
• Active brain metastases. Patients with adequately treated brain metastases may be eligible if they are neurologically stable for at least 2 weeks before enrollment, and are either not requiring corticosteroids or receiving a stable or decreasing dose of ≤10 mg prednisone (or equivalent) once daily.

Other illness

• Histological evidence of mixed small-cell lung cancer (SCLC) or history of transformation to SCLC.

Lab values

• Presence of any other known EGFR mutations.
• Any serious comorbid condition that, in the opinion of the investigator, may interfere with participation in the study or interpretation of study results, including but not limited to: uncontrolled systemic diseases, psychiatric illness, active or uncontrolled infections, or other abnormal findings from laboratory or clinical examinations.

Other

• Pregnancy.

• Age 18-75 years, no restriction on sex.
• Histologically or cytologically confirmed stage III-IV non-squamous NSCLC, unresectable as assessed by multidisciplinary team (MDT).
• Presence of EGFR exon 19 deletion (19Del) or L858R mutation, confirmed by ARMS-PCR, NGS, or other validated methods.
• No prior systemic therapy for lung cancer.
• ECOG performance status of 0-1.
• Estimated life expectancy of at least 6 months.
• Primary lung tumor size ≥1 cm, with at least one measurable lesion remaining after resection according to RECIST v1.1 criteria.
• Adequate organ function, including:
  • ① Hematologic function: absolute neutrophil count ≥1.5 × 10⁹/L; platelet count ≥100 × 10⁹/L; hemoglobin ≥9.0 g/dL.
  • ② Hepatic function: ALT and AST ≤2.5 × ULN (≤5 × ULN if liver metastases are present); total bilirubin ≤1.5 × ULN.
  • ③ Renal function: serum creatinine ≤1.5 × ULN, or creatinine clearance ≥50 mL/min (Cockcroft-Gault formula).
• Adequate pulmonary function (must meet at least one of the following to ensure postoperative reserve):
  • ① FEV1 ≥1.2 L (or ≥40% of predicted value);
  • ② FEV1/FVC ≥0.7, to exclude severe obstructive ventilatory dysfunction;
  • ③ DLCO (diffusing capacity for carbon monoxide) ≥40% of predicted value, to assess diffusion capacity.
  • ④ If preoperative FEV1 \<1.2 L or DLCO \<40%, additional cardiopulmonary exercise testing (e.g., 6-minute walk test, stair climbing test) is recommended to evaluate postoperative pulmonary reserve.
• Evaluated by the study team and deemed suitable for primary tumor resection.
• Signed written informed consent and willingness to comply with study protocol.