Stereotactic Radiotherapy For Locally Residual And Recurrent Nasopharyngeal Carcinoma

Introduction Nasopharynx cavitary is surrounded by many radiation-sensitive critical normal structures, nasopharyngeal carcinoma arises in the mucosa or submucosa of the nasopharynx. The tumor frequently spreads through the foramen lacerum and invades the cavernus sinus. Given both this predilection for the extension and the radiosensitivity of the tumor, radiotherapy is the primary treatment. However, local residual or recurrent disease after radiotherapy is the primary cause of failure. Although higher dose external beam radiotherapy or brachytherapy boosts suggest an increased rate of local control, the possibility of normal tissue injury and/or the inability to effectively treat bulkly tumor are limitations of these techniques. Fractionated Stereotactic radiotherapy (FSRT) has the radiobiologic advantage of conventional fractionation in addition to the mechanical precision by Stereotactic devices. Conformal radiotherapy (CRT) provides a focal and homogeneous dose distribution, sparing the normal tissues. This article is to report the clinical experiences of Stereotactic radiotherapy for locally residual and recurrent nasopharyngeal carcinoma.Method Sixteen patients were treated with Stereotactic radiotherapy between October 1996 and January 2001. Fractionated Stereotactic radiotherapy is applied using the individually made relocatable Gill-Thomas-Cosman (GTC) frame, and the radiation dose planning was performed using Xknife-2. 0 in two patients. Fourteen patientes weretreated with Conformal radiotherapy and the radiation dose planning was performed using Star-2000. Treatment was prescribed at 100% isodose line in all patients. For locally persistent diseases the dose was 3. 5-5Gy/3-6f and for locally recurrent diseases the dose was 3-6Gy/6-10f. Three patients were delivered 20-40Gy/10-20f with external beam radiation in conventional fractionation before SRT. Results All patients are locally controlled at median follow-up 17(3-54) months. The patients with local residual are followed up at median 21.5(7-29) months, patients with local recurrence are followed up at median 16.5(3-54) months. One patient died of torent epistaxis and one died of metastases in patients with locally persistent tumor. Two patients died of torent epistaxis and one died of local tumor progression outside of fields in patients with locally recurrent tumor. The symptom of headache and/or neuroparalysis relieved in two patients and improved in four patients. One patient presented headache and transient trismus after the treament. One patient with headache improved after CRT developed headache aggravating in 13 months. No abnormality was detected after CT scan and the symptom relieved after supporting treatment in the two patients. Conclusion Applying stereotactic radiotherapy for locally residual and recurrent nasopharyngeal carcinoma obtained good treatment result. However, the indication must be defined carefully and the optimal treatment protocal is to be studied.