Hypoxia Imaging -Guided Radiotherapy of Nasopharyngeal Carcinoma

Study Design Patients with previously untreated Stages III~IVA (AJCC 6th Edition) of locally advanced NPC, Karnofsky performance status≥70, and good bone marrow, liver and kidney functions (white blood count ≥ 4.0×109/L, platelets ≥ 100×109/L, albumin ≥30 g/L , creatinine ≤100μmol/L) were enrolled on this study. Patients younger than 18, those with a prior (within 5 years) or synchronous malignancy were excluded. Pretreatment evaluations consisted of a history and physical, dental and laboratory studies. The clinical stage was determined based on all information provided by examinations including contrast enhanced CT and magnetic resonance imaging (MRI) of head and neck, Chest X-ray, liver sonography, bone scan, and 18F-FDG-PET. All tumors were histologically confirmed except those of distant sites.

Patients who met the eligibility criteria were randomized 1:1:1 into the three treatment arms: conventional chemoradiotherapy (group A), FDG PET/CT -guided dose escalation chemoradiotherapy (group B) and FMISO PET/CT -guided dose escalation chemoradiotherapy (group C). All patients were given concurrent chemoradiotherapy within two weeks of diagnosis. Radiotherapy was delivered using the simultaneous modulated accelerated radiation therapy (SMART) IMRT technique in the dose-escalation treatment arms. Concurrent chemotherapy consisted of cisplatin (20mg / m2 ,iv, d1- 4) and docetaxel (75mg / m2, d1, d8) administered on the 1st and 4th week of treatment. All patients received adjuvant chemotherapy that ranged from 2 to 4 cycles.

Follow-up and statistical analysis Planned patient assessment included physical examination and fiberoptic nasopharyngoscopy every 3 months to 3 years starting at 4 weeks post-treatment. A contrast-enhanced CT or MRI of the head and neck is also obtained at each follow up. After 3 years, the patients were followed yearly thereafter. Suspected recurrences were histologically proven. To assess for distant metastasis, CT of the chest and bone scan were obtained every half a year. During every follow-up visit, treatment toxicity were assessed. Radiotherapy-related toxicities were graded according to the Acute and the Late Radiation Morbidity Scoring Criteria of the Radiation Therapy Oncology Group (RTOG) and the European Organization for Research and Treatment of Cancer (EORTC). Chemotherapy-related toxicities (except nausea or alopecia) were graded by the criteria of the WHO.

All events were measured from the date of randomization. OS was defined as the time from the date of radiotherapy to death or the latest date known to be alive. Durations were calculated from the end of treatment. The Kaplan-Meier method was used to calculate the actuarial rates of local control, DFS and OS. The χ2 test was used for comparing incidence rates and categorical variables and Student's t-test was used for comparing the means of continuous variables.