Fibre-optic endoscope-guided three-dimensional high-dose-rate interstitial brachytherapy for residual nasopharyngeal carcinoma after conventional external beam radiotherapy

Purpose
Locally residual nasopharyngeal carcinoma (NPC) is associated with increased risk of local failure, if additional treatment is not applied. The objective of this paper was to report the treatment effect of fibre-optic endoscope-guided three-dimensional high-dose-rate interstitial brachytherapy (3D HDR ISBT) boost, integrated with radical external beam radiotherapy (EBRT) for deep-seated NPC residual lesion.

Case report
A 52-year-old female, with a diagnosis of NPC and biopsy-proven low-differentiated squamous cell carcinoma (SCC) in left nasopharynx; the tumor size was 3.9 × 2.2 × 2.6 cm3 before treatment (T2N0M0). Three months after completion of EBRT, with a dose of 69.96 Gy in 33 fractions and concurrent chemotherapy with cisplatin, the residual tumor (3.3 × 1.8 × 2.2 cm3) was treated with 3D HDR ISBT boost under fibre-optic endoscope guidance. The brachytherapy dose was 14 Gy in 2 fractions of 7 Gy each.

Results
The removal of deep-seated residual tumor was securely achieved by 3D HDR ISBT, guided with fibre-optic endoscope. The refractory tumor in the patient healed uneventfully after fibre-optic endoscope-guided 3D HDR ISBT, without a recurrence during 26 months of follow-up.

Conclusions
Fibre-optic endoscope-guided 3D HDR ISBT boost could be an additional treatment strategy for locoregional residual NPC after radical EBRT, especially for deep invasive lesion.