Local failure patterns for patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy
1 Department of Radiation Oncology, Cancer Center, Sun Yat-Sen University, and State Key Laboratory of Oncology in Southern China, 651 Dongfeng Road East, Guangzhou 510060, P.R. China
2 Department of Radiation Oncology, The First Affiliated Hospital, Sun Yat-Sen University, 58 Zhongshan Road II, Guangzhou 510080, P.R. China
3 Imaging Diagnosis and Interventional Center, Cancer Center, Sun Yat-Sen University, and State Key Laboratory of Oncology in Southern China, 651 Dongfeng Road East, Guangzhou 510060, P.R. China
Radiation Oncology 2014, 9:87 doi:10.1186/1748-717X-9-87Published: 27 March 2014
To investigate the clinical feature and the local failure patterns after intensity-modulated radiotherapy for nasopharyngeal carcinoma.
Between March 2007 and July 2009, 710 patients with nasopharyngeal carcinoma were treated with intensity-modulated radiotherapy. The magnetic resonance imagings obtained at recurrence were registered with the original planning computed tomography for dosimetry analysis.
With a median follow-up of 38 months, 34 patients have developed local recurrence (32 cases valid). The incidence of invasion to nasopharynx, parapharyngeal space and the retropharyngeal space by the primary tumors was 100%, 75.0% and 62.5%, respectively, but 78.1%, 34.4% and 21.9% at recurrence, respectively. The rate of invasion to ethmoid sinus was 3.1% by the primary tumors but 28.1% at recurrence (p = 0.005). The topographic analysis of the local failure patterns showed "central" in 16 patients; "marginal" in 9; and "outside" in 7. The median volumes of primary gross tumor were 45.84 cm3 in the central failure group, 29.44 cm3 in the marginal failure group, and 21.52 cm3 in the outside failure group, respectively (p = 0.012), and the median volumes of primary clinical target1 were 87.28 cm3, 61.90 cm3 and 58.74 cm3 in the three groups, respectively (p = 0.033).
In patients with nasopharyngeal carcinoma treated with intensity-modulated radiotherapy, the recurrent tumors had their unique characteristic and regularity of invasion to adjacent structures. "Central" failure was the major local failure pattern. The volumes of primary gross tumor and clinical target1 were significantly correlated with recurrent patterns. Employ more aggressive approaches to tumor cells which will be insensitive to radiotherapy may be an effective way to reduce the central failure.