2-[18F] Fluorodeoxyglucose Positron Emission Tomography in Predicting Outcome of Patients with Nasopharyngeal Carcinomas Treated by Intensity-Modulated Radiation Therapy

• Main Authors: Jong-Kang, 李永康
• Other Authors: 周明智
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/04157040767760503049

博士 === 中山醫學大學 === 醫學研究所 === 97 === Nasopharyngeal carcinoma (NPC) is an epithelial malignancy compared to other head and neck cancers by its epidemiology, histopathology, clinical characteristics, and treatment. It frequently happened in the Southeast Asia, the Mediterranean basin and the south China. The crude incidence of NPC in Taiwan is 283 cases per 100 thousands people each year. NPC is at the 10th position in incidence of cancer in men and eighteenth in women. As for the death rate, NPC is at the 9th position in men and eleventh in women. Though the incidence of NPC is not high compared to other cancers in Taiwan, the incidence is about 25 to 50 times higher than the general incidence of the world. NPC is highly radiosensitive and chemosensitive. Radiotherapy has been the mainstay treatment for NPC and leads to a high 10-year survival rate if treated in the early-stage. However, there are significantly locoregional recurrence and distant metastases subsequent to radiotherapy in the advanced stage of disease. Identifying predictive factors of outcome in those patients after radio- and chemotherapies has great clinical implications because such factors may allow treatment to be specifically focused on the characteristics of individual tumors. Predictive factors of patient outcome in NPC have traditionally been derived from clinical and pathologic features, e.g., T and N stages, size and degree of fixation of neck nodes, sex, age, the presence of cranial nerve involvement, tumour’s histological type and the radiotherapy dosage and coverage, primary tumor volume, and parapharyngeal extension, etc. While detailed evaluation of these factors, difficulty remains to reliably predict the outcome of treatment in individual patients. The clinical, or even pathological TNM staging is still associated with a heterogeneous survival and relapse pattern, and is thus far from perfect as a prognostic indicator. Due to the high sensitivity in detecting tumors with high glucose metabolism and the capability of whole-body survey in a single examination, positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) has extensively been used in diagnosing the head and neck cancers. Previous studies have shown that use of 18F-FDG PET prior to use of radiotherapy and/or chemotherapy may be useful in predicting improvement in patients with esophageal cancer, cervical cancer, lung cancer, and in non-NPC head and neck cancer. However, the effectiveness of whole-body 18F-FDG PET examining NPC patients prior to use of radiotherapy has rarely been studied. Therefore, the purpose of this study was to investigate the association between the primary tumor FDG uptake, which was measured as the maximum standardized uptake value (SUVmax) at initial diagnosis, and local control (LC) and disease-free survival (DFS) in patients with nonkeratinizing NPC treated with intensity-modulated radiation therapy (IMRT) with or without chemotherapy. One hundred and twelve patients with nonkeratinizing NPC who had received FDG-PET scan prior to radiation therapy combined with or without concurrent chemotherapy were recruited. Primary tumor FDG uptake was measured with the SUVmax. Actuarial LC and DFS and were calculated by the Kaplan-Meier method and evaluated with the log-rank test. The prognostic significance was assessed by univariate analysis. There were 21 patients had definitive radiotherapy and 91 patients received radiotherapy combined with chemotherapy. The mean SUV was significantly higher in the 23 patients who presented with locoregional or distant failure than that in the remaining patients without any such failure (P < 0.001). By univariate analysis, T category showed significant correlations with 3-y LC while the SUVmax for the primary tumor was a significant predictor for both LC and DFS. The T1-2 group had a significantly higher 3-y LC than the T3-4 group (94% vs. 76%; P =.012). Patients with a low (≦ 5.0) SUV had a higher 3-y LC (P < 0.0001) and DFS (P < 0.0001) than those with a high (> 5.0) SUV. For T1-2 patients, 3-y LC was significantly higher in the low SUVmax group (100% vs. 87%; P = 0.012). A similar results were also found in T3-4 patients (100% vs. 59%; P= 0.023). The SUV for the primary tumor was a powerful predictive factor of outcome in treating patients with NPC by CCRT or radiotherapy alone. A high 18F-FDG uptake (SUV > 5.0) was a marker for poor outcome in patients with NPC. Our study indicated that the SUVmax for primary tumors could be an important factor in choosing treatment for patients with NPC.