Local Ablative Stereotactic Radiotherapy for Residual Hypermetabolic Lesion in Patients With Locally Advanced or Metastatic Non-small Cell Lung Cancer Long-term Responders to Immunotherapy

Inclusion Criteria:

* Patient aged 18 or more,
* Patient treated for histologically proven non-small cell lung cancer,
* Stage IIIB or IV,
* Performance status 0 to 2,
* Patient treated by immunotherapy (anti PD-1 or anti PD-L1) started for at least 6 months and regardless of the treatment line (in first line, immunotherapy may have been combined with chemotherapy),
* Response or stable disease on thoraco abdomino pelvic and cerebral CT scan,
* Maximum 5 residual hypermetabolic lesions measured on the 18F-FDG PET / CT centrally reviewed, including primary tumor and a maximum of 3 asymptomatic brain metastases (even if they are poorly seen in 18F- FDG PET/CT) treatable in stereotactic radiotherapy (extracerebral lesions ≤ 4cm and brain lesions ≤ 3cm measured on CT scanners)
* Effective contraception used in women of childbearing potential
* Written informed consent obtained from the patient prior to performing any protocol-related procedures, including screening evaluations,
* Patient is willing and able to comply with the protocol for the duration of the study including undergoing treatment and scheduled visits and examinations including follow up,
* Patient has valid health insurance.

Exclusion Criteria:

* Persistence of grade 2 or greater adverse effects of immunotherapy,
* Infection in progress,
* At least one of the 5 hypermetabolic lesions measured on the 18F-FDG PET / CT centrally reviewed in a previously irradiated area,
* Uncontrolled severe comorbidity,
* History of another primary malignancy except for Malignancy treated with curative intent and with no known active disease ≥ 3 years and of low potential risk for recurrence ; Adequately treated non-melanoma skin cancer or lentigo maligna without evidence of disease ; Adequately treated carcinoma in situ without evidence of disease
* Pregnant or nursing patient
* Patient deprived of liberty or under guardianship,
* Patient unable to undergo regular medical check-ups for geographical, social or psychological reasons.
* Disorder precluding understanding of trial information or informed consent