Reirradiation with Robotic Stereotactic Body Radiotherapy for Recurrent Nasopharyngeal Carcinoma

Background: Recurrent nasopharyngeal carcinoma (NPC) after previous radiotherapy is challenging. Thereis no standard approach for salvage treatment. Here we present toxicity and treatment results for recurrentNFC patients who underwent fractionated stereotactic radiotherapy (FSRT) as second line radiotherapy (RT).Materials and
Methods: Between April 2009 and July 2012, 24 patients, with a male to female ratio of 3:1, weretreated with CykerKnife® FSRT for recurrent NFC in our institution. Seven out of 24 patients had metastaticrecurrent disease. Median age was 53 years (range, 20-70 years). Initial RT dose was 70Gy. The time periodbetween initial RT and FSRT was a median of 33.2 months. The median prescription dose for FSRT was 30Gy(range, 24-30 Gy) in a median of 5 fractions (range, 4-6).
Results: The median follow-up for all patients was19.5 months (IQR: 12.2. -29.2 months). The locoregional control; progression free survival and overall survival(OS) rates for 1-, 2- and 3-year were 64%, 38%, 21%; 60%, 30%, 17% and 83%, 43%, 31%, respectively.Median OS for the entire cohort was 22 months (95% CI: 16.5-27.5). On multivariate analysis recurrent tumorstage was the only prognostic factor for OS (p=0.004). One patient exhibited grade III temporal lobe necrosis.One died because of grade IV mucositis and overlapping infection.
Conclusions: The treatment of recurrentNPC is controversial. Fractionated stereotactic radiotherapy is promising. However, the published trials areheterogeneous with respect to the selection criteria and treatment details. Prospective studies with long termfollow-up data are warranted.