Radiation technique.
toxicity, nonthoracic or abdominal tumors, thoracic or abdominal tumors, tumors
TUMORS, METASTASES
Patients received SBRT to at least 2 measurable metastases with each lesion receiving 30–50 Gy over 3-5 fractions depending on anatomical location (For nonthoracic or abdominal tumors away from the diaphragm, the GTVs were delineated on axial slices from the CT simulation. For thoracic or abdominal tumors closer to the diaphragm with tumors that moved no more than 1cm on 4 DCT, an ITV was generated with the aid of maximum-intensity projection (thoracic) or minimum-intensity projection (abdomen) images. For those that moved more than 1cm on 4 DCT, either a breath-hold approach was utilized to generate a GTV or abdominal compression devices were used to generate an ITV at the discretion of the radiation oncologist. SBRT dose varied by anatomical site: 45 Gy in 3 fractions for peripheral lung, liver, and abdominal/pelvic; 50 Gy in 5 fractions for central lung and mediastinal/cervical/axillary; 30 Gy in 3 fractions for osseous and spinal/paraspinal. If excess toxicity was observed, a reduced dose was specified. Treatment was delivered using photons with linear accelerators once daily on an every-other-day basis within 14 days. Pembrolizumab (200 mg IV every 3 weeks) began within 7 days following the last fraction of SBRT (SBRT+P) and was continued for a maximum of 2 years or until radiographic or clinical progression.