Clinical experience has shown that metastasis can often be limited in number and location, and thus amenable to local treatment. The term oligometastasis describes an intermediate state of cancer spread between localized disease and widespread metastasis. The implication of such an intermediate state is that the disease can be cured by using metastasis-directed therapy. Historically, in some patients with oligometastases in the liver or lungs, surgical resection was often indicated, as abundant evidence suggested it could improve progression-free or overall survival. Recently, several studies have reported promising outcomes of >80% local control with Stereotactic Body Radiotherapy (SBRT) in patients with lung or liver oligometastases. Nonetheless, very few studies have focused on non-liver, non-lung extracranial oligometastatic lesions treated with SBRT, and such studies have limitations of a retrospective nature and small sample sizes.Because allmost studies are based on single-arm studies without appropriate controls, the level of evidence to support SBRT is weak. Randomized trials are therefore necessary to establish the utility of SBRT for oligometastatic disease.

This study is designed as a randomized phase II study. Patients will be randomized between current standard treatment (Arm 1) versus standard treatment +SBRT (Arm 2) to all known disease.

Inclusion Criteria:

• age <18 years old
• ECOG score: 0-2
• number of distant metastases: 1-5
• all cancers (except lymphoma, myeloma, and germ cell tumor)
• status of primary lesion: cured
• pathologically confirmed cancer
• life expectancy: over 6 months

Exclusion Criteria:

• recurrent lesion which had been treated by radiotherapy
• complete response after systemic therapy
• patients who cannot be treated with SBRT due to any reason.
• pregnancy or breast-feeding
• malignant pleural effusion