[Value of 18F-fluorodeoxyglucose positron emission tomography in three-dimensional conformal radiotherapy for locally persistent or recurrent nasopharyngeal carcinoma].

Objective: To explore the clinical value of (18)F-fluorodeoxyglucose positron emission tomography ((18)FDG-PET) in three-dimensional conformal radiotherapy (3D-CRT) for locally residual and recurrent nasopharyngeal carcinoma (NPC).

Methods: Between July 1998 and October 2000, 36 patients with recurrent or residual NPC confirmed by biopsy after initial radiotherapy underwent treatment with 3D-CRT. CT simulation was performed and (18)FDG-PET carried out for delineating the gross tumor volume (GTV) in all the patients. The radiotherapy was designed by 3D treatment planning system and dose-volume histogram (DVH) was used to verify and optimize the radiation plan. Acute and late radiation injuries, survival rates and GTV delineated by CT and (18)FDG-PET were observed in all the cases after the treatment.

Results: In comparison with CT simulation, (18)FDG-PET delineated similar GTV in 36.1% (13/36) cases, larger and smaller GTV in 16.7% (6/36) and 47.2% (17/36) of the cases, respectively. After 3D-CRT, 97.2%, 75.0%, and 58.3% of the patients were free of evidence of 1-, 2-, and 3-year local failure, respectively, and the 1-, 2-, and 3-year survival rate of the patients were 94.4%, 86.1%, and 72.0%. The 1-, 2-, 3-year tumor-free survival rates were 85.7%, 76.6%, and 56.1% respectively. Acute xerostomia, nasopharyngitis and oropharyngitis were the most common complications in relation to the radiation, but all within acceptable range of grades 1 or 2. The lesions resulting from the radiation included hearing loss, trismus, dysphagia, chronic sinusitis, and cranial neuropathy, with the incidences of 5.6% (2/36), 25.0% (9/36), 8.3% (3/36), 33.3% (12/36), and 13.9% (5/36) respectively.

Conclusions: 3D-CRT combined with (18)FDG-PET for delineation of GTV is effective and feasible in the treatment of locally residual or recurrent nasopharyngeal carcinoma after initial radiotherapy, producing good responses without serious complications.