2.2 Inclusion and exclusion criteria
The inclusion criteria were as follows: (1) NPC confirmed by pathology; (2) relapse after EBRT and unable or rejecting to undergo surgery or re-irradiation; (3) tumor diameter ≤7cm; (4)pre-plan shown a feasible needle pathway to avoid bones, large blood vessels or organs at risk (OARs); (5) Karnofsky Performance Status (KPS) ≥60; (6) expected survival ≥3 months. The exclusion criteria were as follows: (1) severe bleeding tendency; (2) immunocompromised with acute infection or chronic active infection; (3) patient with conditions intolerant to minimal invasive procedure/surgery such as severe cardiopulmonary insufficiency or liver and kidney; (4) contraindication to anesthesia; (5) uncontrolled multiple metastases.