Consolidative Stereotactic Radiotherapy for Oligo-Residual Advanced EGFR-Mutant NSCLC After First-Line Third-Generation EGFR-TKI Plus Chemotherapy

Inclusion Criteria:

* Histologically confirmed non-small cell lung cancer.
* Clinical stage IV disease according to the AJCC 9th edition.
* Sensitizing EGFR mutation: EGFR exon 19 deletion or EGFR L858R.
* Age 18-75 years.
* Karnofsky Performance Status score ≥70.
* Complete whole-body imaging assessment before initiation of first-line third-generation EGFR-TKI plus chemotherapy, with at least one evaluable lesion according to RECIST version 1.1.
* No disease progression after completion of four cycles of first-line third-generation EGFR-TKI plus chemotherapy and no unresolved grade ≥3 nonhematologic toxicity.
* Oligo-residual disease after four treatment cycles, with all residual lesions considered suitable for stereotactic radiotherapy by the investigator.
* Written informed consent.

Exclusion Criteria:

* Double primary or multiple primary malignancies, except early skin cancer or cervical carcinoma in situ treated with curative intent and without recurrence or progression for at least five years.
* Pregnancy or breastfeeding, or considered unsuitable by the investigator for PET/CT or brain MRI examination.
* History of uncontrolled epilepsy, central nervous system disease, or psychiatric disorder that, in the investigator's judgment, may interfere with informed consent or participant compliance.
* Residual lesions considered unsuitable for consolidative stereotactic radiotherapy after first-line third-generation EGFR-TKI plus chemotherapy.