3 DCT implanted interstitial brachytherapy for T 2 b nasopharyngeal carcinoma

Background: To compare the results of external beam radiotherapy in combination with 3Dcomputed tomography (CT)-implanted interstitial high dose rate brachytherapy (ERT/3D-HDR-BT) versus conventional external beam radiotherapy (ERT) for the treatment of stage T2b nasopharyngeal carcinoma (NPC). Methods: Forty NPC patients diagnosed with stage T2b NPC were treated with ERT/3D-HDR-BT under local anesthesia. These patients received a mean dose of 60 Gy, followed by 12-20 Gy administered by 3D-HDR-BT. Another 101 patients diagnosed with non-metastatic T2b NPC received a mean dose of 68 Gy by ERT alone during the same period. Results: Patients treated with ERT/3D-HDR-BT versus ERT alone exhibited an improvement in their 5-y local failurefree survival rate (97.5% vs. 80.2%, P = 0.012) and disease-free survival rate (92.5% vs. 73.3%, P = 0.014). Using multivariate analysis, administration of 3D-HDR-BT was found to be favorable for local control (P = 0.046) and was statistically significant for disease-free survival (P = 0.021). The incidence rate of acute and chronic complications between the two groups was also compared. Conclusions: It is possible that the treatment modality enhances local control due to improved conformal dose distributions and the escalated radiation dose applied. Introduction In 1996, Chua et al. [1] reported the incidence of parapharyngeal extension in NPC patients to be as high as 72.5%. Of these patients, 65.5% exhibited extensions into the prestyloid space and/or the masticator space, which was associated with lower rates of 5-year local control and distant metastasis-free survival. Numerous studies also showed that parapharyngeal extension was an unfavorable prognosis factor in predicting overall relapse, local relapse, and distant metastasis [2-4]. Over the past few decades, two-dimensional brachytherapy (2D-BT) has been used to apply high doses of radiation directly to the primary tumor, while sparing nearby critical normal tissues. Some studies have reported that brachytherapy significantly enhances local control and the overall survival rate for early T-stage NPC [5,6], but 2D-BT may provide less adequate target volume coverage if the tumor has extended into the parapharyngeal space. 3D-computed tomography (CT)implanted interstitial HDR brachytherapy (3D-HDR-BT) was developed from 2D-BT techniques [7-9], and with this approach, the target volume, as well as all of the vital structures involved, can be outlined using Plato software (PLATO BPS 14.2, Nucletron B.V, Veenendaal, The Netherlands). Reconstruction and 3D planning of interstitial implants with non-parallel applicators also use Plato software, as well as a real-time evaluation of the isodose distribution achieved in all CT slices. Accordingly, this interstitial implantation technique has been applied to the treatment of prostate cancer [10,11], breast cancer [12], rectal carcinoma [13], and cervical cancer [14]. However, there are no reports of the treatment results achieved using 3D-HDR-BT for the treatment of NPC. Therefore, the goal of this current study is to evaluate the local control and distant metastasis events exhibited by stage T2b NPC patients that received ERT with or without additional 3D-HDR-BT therapy. * Correspondence: caoxp@sysucc.org. cn † Contributed equally State Key Laboratory of Oncology in Southern China, Department of Radiation Oncology, Cancer Center, Sun Yat-sen University, 651 Dongfeng Road East, Guangzhou, PRC Full list of author information is available at the end of the article Ren et al. Radiation Oncology 2010, 5:113 http://www.ro-journal.com/content/5/1/113 © 2010 Ren et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Methods and Materials Patient characteristics Forty NPC patients diagnosed with stage T2b disease at the Cancer Center of Sun Yat-Sen University (Guangzhou, People’s Republic of China) between January 2004 and February 2008 were prescribed ERT with 3D-HDRBT. To evaluate the efficacy of this treatment modality, these 40 cases were retrospectively compared with 101 patients diagnosed with non-metastatic T2b disease that were treated with ERT alone during the same period. For the two patient groups, the male/female ratio was about 3:1 with 104 males and 37 females, and the median age was 44 years (range, 19-80 years). Histological examination showed that 97.2% of the patients had World Health Organization (WHO) type II or III disease, 4 patients had type I disease. Each patient was confirmed by biopsy, direct fiberoptic examination, complete blood count, blood chemistry test, chest X-ray, bone scan, and the extension of disease was further evaluated by physical examination, magnetic resonance imaging (MRI) of the nasopharynx and neck. Gross disease was carefully diagrammed for each patient and all MRI materials and clinical records were reviewed to minimize heterogeneity in restaging. Two radiologists specializing in head-and-neck cancers evaluated all scans and any disagreements were resolved by consensus. All stage T2b patients were restaged according to the American Joint Committee on Cancer staging system (6 edition) [15]. Acute and late complications were scored according to criteria of the Radiation Therapy Oncology Group (RTOG) scoring system.