PURPOSE: This study aims to investigate the feasibility of contouring target volume according to residual tumor and decreasing the dose to the tumor regression field after induction chemotherapy (IC) in locoregionally advanced nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS: From August 2009 to August 2013, patients with stage III–IVB NPC were treated with IC and concurrent chemoradiotherapy. Gross tumor volume of nasopharynx (GTVnx)–residual and gross tumor volume of cervical lymph node (GTVnd)–residual were contoured according to post-IC residual primary tumor and any N+ disease, respectively. The tumor regression field was included in CTVnx1/CTVnd1 and prescribed a dose of 60 Gy. Outcomes and toxicities of all patients were evaluated. RESULTS: A total of 57 patients were enrolled. At a median follow-up of 68 months, three cases displayed locoregional recurrence and one case showed both distant metastasis and locoregional recurrence. All locoregional recurrences were in the GTVnx-residual/GTVnd-residual and in-field. The 5-year overall, locoregional relapse-free, distant metastasis-free, and progression-free survival rates were 82.2%, 87.7%, 85.8% and 80.3%, respectively. CONCLUSION: After IC, contouring of GTVnx-residual/GTVnd-residual as residual tumor volume and distribution 60 Gy ofradiation dose to the tumorregression field may be feasible and need further investigation.
Chemoradiotherapy ; Disease-Free Survival ; Follow-Up Studies ; Humans ; Induction Chemotherapy ; Lymph Nodes ; Nasopharynx ; Neoplasm Metastasis ; Neoplasm, Residual ; Radiotherapy, Intensity-Modulated ; Recurrence ; Tumor Burden

Objective:To investigate the clinical efficacy of concurrent chemotherapy in intensity-modulated radiotherapy (IMRT) for patients with stage Ⅲ nasopharyngeal carcinoma (NPC).Methods:Clinical data of 251 patients with stage Ⅲ NPC treated with IMRT alone or concurrent chemoradiotherapy (CCRT) at Sun Yat-sen University Cancer Center from February 2001 to December 2008 were retrospectively analyzed. The prognostic factors of NPC were analyzed and the efficacy of CCRT was assessed. The survival rate was calculated by Kaplan-Meier method. The differences between two groups were analyzed by log-rank test. The prognostic factors were analyzed by Cox model.Results:The 10-year locoregional-free survival (LRFS), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS) for NPC patients were 88.6%, 81.1%, 68.8% and 75.1%, respectively. Univariate and multivariate analyses demonstrated that N staging and nasopharyngeal tumor volume were the most important prognostic factors, and concurrent chemotherapy significantly improved PFS and OS (both P<0.05). In T 3N 0-1 patients, there was no significant difference in survival indexes between IMRT alone and CCRT (10y-LRFS: 93.8% vs. 93.2%, P=0.933; 10y-DMFS: 80.9% vs. 86.8%, P=0.385; 10y-PFS: 70.6% vs. 77.7%, P=0.513; 10y-OS: 71.8% vs. 83.6%, P=0.207). For T 1-3N 2 patients, CCRT was significantly better than radiotherapy alone in LRFS, PFS, and OS (10y-LRFS: 87.3% vs. 66.7%, P=0.016; 10y-PFS: 70.2% vs. 41.0%, P=0.003; 10y-OS: 78.5% vs. 51.7%, P=0.008), whereas there was an increasing trend in DMFS (10y-DMFS: 80.3% vs. 66.4%, P=0.103). Conclusions:Concurrent chemotherapy can improve clinical prognosis of stage Ⅲ NPC patients, and the most survival benefits are obtained in the N 2 group. Individualized treatment options should be delivered based on the risk of treatment failure.

Objective:To investigate the necessity of adaptive re-planning during radiotherapy for nasopharyngeal carcinoma (NPC) and its impact on dose improvement.Methods:Clinical data of 89 NPC patients admitted to Sun Yat-sen University Cancer Center from July 2014 to December 2017 were retrospectively analyzed. All patients received 25+7 rounds of adaptive re-planning during radiotherapy. Plan-A was defined as the initial CT scan-based 25-fraction radiotherapy plan, while plan-B was defined as the re-planned 7-fraction radiotherapy plan based on a subsequent CT scan. The changes in the target and parotid gland volumes were compared between plan-A and plan-B. Plan-I was a one-time simulation of plan-A extended to 32 fraction radiotherapy plan, and plan-II was generated through registration and fusion of the plan-A and plan-B for adaptive re-planning. The differences in dose metrics, homogeneity index (HI), conformity index (CI), and dose to organs at risk (OAR) were compared between plan-I and plan-II. Statistical analysis was performed by using paired t-test. Results:Compared with plan-A, the gross tumor volume of massive bleeding lesions (GTV nx) and parotid gland volume of plan-B were decreased by 13.14% and 11.12%, respectively (both P<0.001). While planning clinical target volume of metastatic lymph nodes (PCTV nd) of plan-B was increased by 7.75%( P<0.001). There were significant changes in the lymph nodes of plan-A and plan-B. The D mean, D 5%, D 95% of massive bleeding lesions planning target volume (PTV nx) and D 5% of high risk planning target volume (PTV1) in plan-II were all significantly higher than those in plan-I (all P<0.05). The CI of PTV nx and PTV1 in plan-II was closer to 1 than that in plan-I. In all assessed OAR, the D mean, D 50%, and D max of plan-II were significantly lower than those of plan-I (all P<0.05). Conclusions:During radiotherapy, NPC patients may experience varying degrees of primary tumor shrinkage, parotid gland atrophy, and lymph node changes. It is necessary to deliver re-planning and significantly improve the dose of target areas and OAR.