Study On The Curative Effect Of Intensity Modulated Radiation Therapy For Nasopharyngeal Carcinoma And The Failure Mode Of Local Region

Part Ⅰ:Clinical results for nasopharyngeal carcinoma treated with intensity-modulated radiotherapyPurpose:To evaluate the survival and toxicity of patients with nasopharyngeal carcinoma (NPC) treated by intensity-modulated radiotherapy (IMRT).Methods and materials:This is a retrospective analysis of 364 NPC patients. All the patients were treated with IMRT in Fudan University Shanghai Cancer Center between 12/2007 and 04/2012. Cisplatin-based chemotherapy was given to the patients with local-regional advanced disease. Adverse events were evaluated according to the National Cancer Institute Common Toxicity Criteria for Adverse Events version 3.0 (NCI-CTCAE). The Kaplan-Meier method was used to estimate the cumulative survival rates. Univariate analysis was performed using log-rank test. Factors with univariate p< 0.25 were included in a multifactor Cox model to determine the independent prognostic factors.Results:The median follow-up time was 40 months (range 3-84 months).35 patients experienced local regional failure and total distant metastasis occurred in 55 patients, representing the major mode of failure.45 patients died. Among them,64.4% died of distant metastasis. The 3-year local failure-free survival (LFFS), regional failure-free survival (RFFS), distant metastasis-free survival (DMFS), overall survival (OS), and progression-free survival (PFS) were 94.1%、95.4%、 86.5%、90.9% and 78.7%, respectively. Grade 3 dermatitis and mucositis occurred in 27 patients (7.4%),160 patients (44%). No Grade 4 acute toxicities were observed. Multi-factor analysis showed that T stage was an independent prognostic factor for LFFS、RFFS、DMFS、OS and PFS. N stage was an independent prognostic factor for DMFS and PFS.Conclusions:IMRT provides excellent local-regional control for NPC, with acceptable acute and late toxicities. Distant metastasis remains the most difficult treatment challenge. More effective systemic chemotherapy should be explored.Part II:Patterns of local-regional failure after primary intensity modulated radiotherapy for nasopharyngeal carcinomaBackground:To analyze patterns of local-regional failure after intensity modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC).Methods:Patients with local-regional recurrence in part I were included in this study. The location and extent of local-regional failures were transferred to the pretreatment planning computed tomography (CT) for dosimetric analysis. The dose of radiation received by Vrecur (volume of recurrence) was calculated and analyzed with dose-volume histogram (DVH). Failures were classified as:"in field" if 95% of Vrecur Was within the 95% isodose, "marginal" if 20% to 95% of Vrecur was within the 95% isodose, or "outside" if less than 20% of Vrecur was inside the 95% isodose.Results:A total of 35 patients suffered local-regional recurrence. Among them,29 patients were eligible for analysis. The median age was 47 years old (range from 37 to 76 years old).91.4% of the patients were attributed to stage III-IV according to the AJCC2010 staging system Stage. The median time from treatment to recurrence was 26 months (range from 11 to 57 years old). The 3-year actuarial local-regional control rates for all patients were 90.9%. Among the 37 local-regional failures with available diagnostic images,30 (81.1%) occurred within the 95% isodose lines and were considered in-field failures; 3 (8.1%) were marginal and 4 (10.8%) were outside-field failures.Conclusions:In-field failures are the main patterns for local-regional recurrence after primarily intensity-modulated radiotherapy in NPC. This suggests that low sensitivities to radiotherapy of cancer cells is an important reason for local-regional failure.