Preliminary results of locally recurrent nasopharyngeal carcinoma treated with intensity modulated radiation therapy / 中国癌症杂志

ABSTRACT

Purpose:To evaluate the physical dose distributions and tolerance in locally recurrent nasopharyngeal carcinoma treated with intensity modulated radiation therapy (IMRT).Methods:From June 1999 to August 2000, 10 patients with locally recurrent nasopharyngeal carcinoma proven by histology, without neck lymphoid node recurrence and distant metastasis, were treated by IMRT. The interval from the time of initial radiotherapy to recurrence ranged from 14—50(median 25) months. The initial radiotherapy in all patients were treated with external radiotherapy alone to a median dose of 69Gy/35fractions/52days. IMRT method was performed by means of the MIMiC collimator and inverse treatment planning system (NOMOS company, USA). The prescribed dose of re radiotherapy to target volume was 57Gy/19fractions/4weeks.Results:All patients, except for some patients with mild weight loss and reaction in the oral cavity during radiotherapy, tolerated this IMRT well. IMRT achieved the better immediate responses in 10 patients with complete response in 6 cases and partial response in 4 cases. Recurrence was found in two patients, lung distant metastasis in one patient. The median survival in the 10 patients was 14 months. The median planning target volume (PTV) was 95.8(60—134) cm 3. The dose distributions in the PTV were as follows median average dose 59.65?2.47Gy, median homogeneity index (HI) 1.18(?0.06); median dose to 95% PTV ≥ 53.2 (?1.36)Gy. The median dose to the organs at risk (OAR) were as follows spinal cord 9.46?5.23Gy; brain stem 20.24?3.55Gy; left parotid gland 18.53?5.30Gy, right parotid gland 19.68?6.21Gy; left lens 2.11?0.65Gy, right lens 2.94?0.57Gy;Chiasm12.34Gy; left optical nerve13.14 Gy, right optical nerve17.65 Gy.Conclusions:Better dose distributions treated with IMRT was achieved in the patients with locally recurrent nasopharyngeal carcinoma and the patients tolerated this radiotherapy well. [