Comparison of Stereotactic Radiosurgery and Radiotherapy in Salvaging Local Failures of Nasopharyngeal Carcinoma

Local failure is an important cause of treatment failure in nasopharyngeal carcinoma (NPC). Although surgery and brachytherapy can be used as salvage treatment in selected cases, most patients with local failure of NPC require external reirradiation. Both stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) have been employed in reirradiation of NPC, but the relative efficacy of these two techniques is not known. Records of 125 NPC patients who received SRS or SRT in two centers were reviewed. Patients who received treatment as a planned boost after external radiotherapy and those with disease elsewhere were excluded. A matched-pair study was used to select and analyze the outcome of patients. A total of 86 patients were included in the study, with equal number of patients treated by SRS and SRT. All patients were individually matched for type of failure (persistent if ≤6 months of 1st radiotherapy vs. recurrent if >6 months), retreatment T stage (rT1-2 vs. rT3-4), and tumor volume (≤5 cc vs. >5–10 cc vs. >10 cc). Median dose was 12.5 Gy in single fraction by SRS, and 34 Gy in 2–6 fractions by SRT. Median follow-up was 34 months for SRS group and 18 months for SRT group. Local control was better in patients treated by SRT, but there was no significant difference in overall survival. One- and 3-year local failure-free rates were 70% and 51% in SRS group compared with 91% and 83% in SRT group (p = 0.003). One- and 3-year overall survival rates were 98% and 66% in SRS group compared with 78% and 61% in SRT group (p = 0.31). The differences in local control were mainly observed in patients treated for recurrent or rT2-4 disease, with no significant differences in local control using either technique in persistent or rT1 disease. Severe late complications occurred in 33% of patients in SRS group and 21% in SRT group, including brain necrosis (16% vs. 7%), brain stem necrosis (0 vs. 5%), mucosal necrosis (0 vs. 12%), and hemorrhage (5% vs. 2%). This retrospective study showed that SRT was superior to SRS in salvaging local failures of NPC, especially in patients with recurrent and rT2-4 disease. In patients with local failure of NPC, SRT may be the preferred technique of reirradiation compared with SRS.