Weekly Plasma EBV DNA for Non-metastatic Nasopharyngeal Carcinoma

Overview

Nasopharyngeal carcinoma (NPC) is an endemic malignancy in Southern China, Hong Kong, Taiwan, Singapore and Malaysia. It is highly associated with Epstein-Barr virus (EBV). Radiation therapy alone is indicated for early stage I to II diseases while concurrent chemoradiation is required for more advanced stage III to IVB diseases. Intensity-modulated radiation therapy (IMRT) is the standard radiation technique for NPC, in virtue of its superior target coverage and dose sparing to adjacent critical organs-at-risks. Plasma EBV DNA and other novel plasma biomarkers have been extensively investigated in NPC. Previous studies have proven their predictive and prognostic values in NPC diagnosis, surveillance and survival outcomes. Investigators would like to investigate the roles of plasma biomarkers including plasma EBV DNA on treatment response evaluation, survival and prognosis on NPC, in the modern era of precision radiation therapy. This will help provide important information on refining on the current edition of AJCC/UICC staging classification.

Patients with histologically confirmed previously untreated NPC are be recruited to join tis study. The study has obtained approval from local institutional review board. After written informed consent, baseline investigations including blood tests for routine hematology, biochemistry and plasma EBV DNA will be taken. Only 3ml of EDTA blood will be taken for plasma EBV DNA and other potential biomarkers. Patients will also undergo baseline imaging investigations including positron-emission tomography with integrated computed tomography (PET-CT) and magnetic resonance imaging (MRI) of the head and neck regions. An routine nasoendoscopy and nasopharyngeal biopsies will be obtained to confirm and delineate the mucosal extent of the disease. If confirmed non-metastatic, patients will be treated with IMRT using 7-9 radiation beams. A total dose of 70Gy in 33-35 fractions over 6.5 to 7 weeks will be given. For advanced stage III to IVB diseases, concurrent chemoradiation using cisplatin 100mg/m2 on Day 1, 22 and 43 of IMRT followed by 3 cycles of adjuvant chemotherapy with cisplatin 80mg/m2 on Day 1 and 5-FU 1000mg/m2 from Day 1 to Day 4 every 4 weeks for 3 more cycles starting 4 weeks after completion of IMRT will also be given. Some patients will also receive induction chemotherapy with cisplatin100mg/m2 on Day 1 and 5-FU 1000mg/m2 on Day 1 to 5, administered every 3 weeks for 3 cycles before commencement of chemoradiation, at the discretion of treating oncologists if the primary tumours are close to critical organs e.g. brainstem, optic chiasm or optic nerves. After treatment patients will undergo nasopharyngeal biopsies, patients will undergo nasopharyngeal biopsies again at 8 weeks after completion of IMRT to confirm histological complete local remission. Blood will be taken again on the same day for plasma EBV DNA and other potential biomarkers. Additional biopsies and salvage local treatment e.g. brachytherapy, stereotactic or IMRT boost will be offered to patients who have persistent local disease at 12 weeks after completion of IMRT. If complete local remission is confirmed, patient will have regular follow up every 3 to 4 months for surveillance and survival outcomes. Regular imaging with MRI and CT scans every 3 to 4 months will also be arranged as well. Plasma EBV DNA will be measured at weekly intervals until EBV DNA is undetectable. For those with metastatic diseases, systemic chemotherapy (platinum-based chemotherapy) will be offered. Blood taking for plasma EBV DNA and other potential biomarkers at baseline before chemotherapy commencement and then after every 3 cycles will be arranged. Imaging examinations with CT and MRI scans will be arranged at baseline and then after 3-4 cycles of chemotherapy for tumour response evaluation. The trend of baseline and serial plasma EBV DNA will be monitored prospectively.