J Korean Neurosurg Soc.  2020 May;63(3):397-405. 10.3340/jkns.2019.0011.

Gamma Knife Radiosurgery Using Co-Registration with PET-CT and MRI for Recurrent Nasopharyngeal Carcinoma with Previous Radiotherapy : A Single Center 14-Year Experience

• Lee C
• Park SH
• Yoon SY
• Park KS
• Hwang JH
• Hwang SK

• KMID: 2501728
• DOI: http://doi.org/10.3340/jkns.2019.0011

Abstract

Objective
: We retrospectively evaluated the efficacy of Gamma Knife radiosurgery (GKS) for recurrent nasopharyngeal carcinoma (NPC) in patients who previously underwent radiotherapy, and analyzed the treatment outcomes over 14 years.
Methods
: Ten patients with recurrent NPC who had previously received radiotherapy underwent stereotactic radiosurgery using a Gamma Knife^® (Elekta Inc, Atlanta, GA, USA) between 2005 and 2018. The median target volume was 8.2 cm³ (range, 1.7–17.8), and the median radiation dose to the target was 18 Gy (range, 12–30). The median follow-up period was 18 months (range, 6–76 months). Overall and local failure-free survival rates were determined using the Kaplan-Meier method.
Results
: The NPCs recurred at the primary cancer site in seven patients (70%), as distant brain metastasis in two (20%), and as an extension into brain in one (10%). The recurrent tumors in seven of the 10 patients (70%) were found on the routine follow-up imaging studies. Two patients presented with headache and one with facial pain. Local failure after GKS occurred in five patients (50%) : two of whom died eight and 6 months after GKS, respectively. No adverse radiation effects were noted after GKS. The 1- and 3-year overall survival rates after GKS were 90% and 77%, respectively. The local failure-free survival rates at 6 months, 1 year, and 3 years after GKS were 80%, 48%, and 32%, respectively. The median interval from GKS to local failure was 8 months (range, 6–12). Univariate analysis revealed that using co-registration with positron emission tomography-computed tomography (PET-CT) and magnetic resonance imaging (MRI) was associated with a lower local failure rate of recurrent NPC (p=0.027).
Conclusion
: GKS is an acceptable salvage treatment option for patients with recurrent NPC who previously received radiation therapy. PET-CT and MRI co-registration for dose planning can help achieve local control of recurrent NPC.

Keyword

Radiosurgery; Nasopharyngeal carcinoma; Positron emission tomography computed tomography

Figure

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  Fig. 1. A : Dose planning for recurrent nasopharyngeal carcinoma showing co-registration with PET-CT and MRI. The tumor was treated with a radiation dose of 20 Gy at the 50% isodose line. B : Dose planning for recurrent nasopharyngeal carcinoma showing MRI without co-registration with PET-CT. PET-CT : positron emission tomography-computed tomography, MRI : magnetic resonance imaging.

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  Fig. 2. A : Dose planning for recurrent nasopharyngeal carcinoma showing MRI without co-registration with PET-CT. It was difficult to accurately define the tumor on MRI without co-registration with PET-CT. PET-CT images obtained at other hospitals were not adjustable for co-registration on our hospital's workstation computer. The ill-defined tumor was treated with a radiation dose of 18 Gy at the 50% isodose line. B : PET-CT showing tumor recurrence (arrow) 8 months after Gamma Knife radiosurgery. C : The tumor was re-treated with a radiation dose of 20 Gy at the 50% isodose line. MRI : magnetic resonance imaging, PET-CT : positron emission tomography-computed tomography.

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  Fig. 3. Kaplan-Meier curve showing local failure-free survival of patients with recurrent nasophar yngeal carcinoma af ter Gamma Knife radiosurgery.

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  Fig. 4. Kaplan-Meier curves showing local failure-free survival of patients with recurrent nasopharyngeal carcinoma after Gamma Knife radiosurgery according to the use of co-registration with PET-CT and MRI. The difference between the two groups was significant (p=0.027). PET-CT : positron emission tomography-computed tomography, MRI : magnetic resonance imaging.

Reference

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