Efficacy and Prognosis of CT-Guided Implantation of 125I Seeds As Salvage Treatment for Recurrent Nasopharyngeal Carcinoma after External Beam Radiotherapy--a Long-Term Experience at a Single Institution

Abstract

To assess the safety and efficacy of computed tomography (CT)-guided 125I seeds implantation for recurrent nasopharyngeal carcinoma (NPC) after external beam radiotherapy (EBRT). Twenty-nine patients with recurrent NPC (thirty-nine lesions) after EBRT from February 2003 to December 2017 were enrolled. All the patients experienced preoperative assessment, patient immobilization, and CT scan, preoperative planning, 125I seeds implantation, postoperative dosimetry assessment, and postoperative care. Median radioactivity of 125I seeds was 0.61 (range, 0.22-0.79) mCi. Median number of implanted seeds was 34 (3-83). Median value of D90 was 136 (62.4-246) Gy. The adverse event was evaluated by the Radiation Therapy Oncology Group (RTOG) classification criteria. Overall survival (OS), local control (LC), local progression-free survival (LPFS), were investigated for their relationship with the prognosis. Median duration of follow-up was 13.7 (4.4-71.2) months. Median duration of LC was 31.6 (2.1-60.2) months. LC at 1, 3, and 5 years was 69.0%, 46.7% and 18.7%, respectively. Median duration of OS was 33.4 (4.4∼71.2) months. OS at 1-, 3- and 5-years was 73.8%, 40.8% and 40.8%, respectively. Median duration of LPFS was 22.6 (3.0-60.2) months. LPFS at1-, 3- and 5-years was 72.0%, 38.7% and 38.7%, respectively. Univariate analysis suggested that sex(P=0.048) and frequency of previous external beam radiotherapy (P=0.018) were prognostic factors influencing survival without local recurrence. Moreover, sex (P=0.023), frequency of previous EBRT (P=0.001), time from the first EBRT to seeds implantation (P=0.007), and D90 (P=0.049) were prognostic factors influencing LC. Multivariate retrospective analysis indicated that sex (P=0.03) was an independent prognostic factor for survival without local recurrence. Prevalence of side effects (≥grade 3) was 20.7%. 125I seeds implantation was a safe and feasible salvage treatment for recurrent NPC after EBRT.